Microbiology & Parasitology Topic 1 PDF

MICROBIOLOGY & PARASITOLOGY RNB 10102 Topic 1: Value of Microbiology  Learning Outcomes At the end of the session, student should be able to define microbiology identify the importance of microbe in our life identify the importance of individuals or scientist contribution t...

MICROBIOLOGY & PARASITOLOGY RNB 10102 Topic 1: Value of Microbiology  Learning Outcomes At the end of the session, student should be able to define microbiology identify the importance of microbe in our life identify the importance of individuals or scientist contribution to microbiology discuss the importance of Koch’s Postulates, Edward Jenner’s and Louis Pasteur's work, explain the germ theory of disease compare spontaneous generation and biogenesis  Introduction to Microbiology The modern science of microbiology began about 100 years ago The word microbiology is derived from the Greek word micros meaning “small” bios meaning “life” and logy means the study of” Microbiology is the branch of biology (study of living thing) that deals with simple life foams, usually single cell that cannot be seen with the naked eye – known as microbes or microorganism Introduction to Microbiology The study of microbiology helps nurses to: Learn how the disease-producing microorganisms enter into the body How they exit from the body How they spread from person to person Understand the principles of disinfection and effects of drugs on microorganism Recognize the importance of proper collection of specimens for bacteriological examination in the lab and understands the meaning of reports from the laboratory  Microbiology What is microbiology? Micro – means very small, bio-life, logy – means study of living things. Therefore microbiology means the study of microorganism or microbes too small to be seen with the naked eye. These microorganism include bacteria, algae, protozoa, fungi and virus.  Microbiology Microbes in our lives: Only a small percentage of microorganism is capable of causing disease (pathogenic ) Majority of microorganism helps maintain balance of live in our environment. E.g. : Marine and freshwater microbes create food chain in the lakes, ocean and rivers Soil microbes helps to break down waste and an integrate nitrogen gas from into organic compound  Microbiology Microbes in our lives: Certain microbes plays important role in photosynthesis, food and oxygen-generating process Human depends on the microbes in the intestine for digestion and synthesis of some vitamins such as vitamin B for metabolism and vitamin K for blood clotting.  Microbiology Microbes in our lives: Commercially use to produce Vitamin B2 (riboflavin) and Vitamin B 12 Food industry uses it to produce vinegar, pickles, yogurt, soya source, cheese, bread and alcoholic beverages. Enzymes from microbes can be used to produce cellulose, digestive aids, drain cleaner and important therapeutic substance insulin  Microbiology Microbes in our lives: Practical knowledge microbes is necessary for medicine and the related health sciences E.g. health workers must be able to protect patient from common microbes that are normally harmless but can threaten the sick and injured.  History of Microbiology Anton Van Leeuwenhoek (1632-1723) Started the field of microbiology Used 300X magnification lenses to observe microorganisms, including protozoa, algae, yeast, fungi and bacteria what he terms as ‘animalcules” First person to observe microorganism Known as “Father of microscopy”  History of Microbiology Robert Hooke (1665) Popularized the use of compound microscope Laid groundwork for the development of cell theory Cell theory. All living things are composed of cells and come from pre-existing cell  Theory of Spontaneous generation (1650- 1850) Spontaneous generation theory: Many scientist and philosophers believes that some form of life could arise spontaneously from non-living matters. They called this hypothetical process spontaneous generation. “Vital force” forms life For example; many believed that flies could develop directly from rotting meat Theory of Spontaneous generation (1650- 1850) Biogenesis theory: Hypothesis that living organisms arises only from preexisting living cells.  Spontaneous generation (1668 – 1859) Francesco Redi (1626 -1697) Among the first to question spontaneous generation Perform a set of experiments in the late 1668 to disprove spontaneous generation  Redi’ experiment Redi filled jar with decaying meat Conditions Results 1 jar covered with fine net No maggot 2 open jars Maggot appeared Where did the maggot comes from? What is the purpose of the sealed jar? Is this Spontaneous generation or biogenesis?  John Tyndall (1668-1859) Showed that “optically pure” (extremely filtered) air contains no microorganisms He compared what happened when he left fish or meat in such pure air or in an ordinary air The preparation in the ordinary air gradually went putrid and maggoty, but the preparation left in the pure air did not deteriorate Spontaneous generation or biogenesis?  The golden age of Microbiology (1857-1914) Beginning with Pasteur’s work, discoveries included the relationship between microbes and disease, immunity and microbial drugs  Louis Pasteur (1822 – 1895) French biologist, microbiologist and chemist renowned for his discoveries of the principles of vaccination, microbial fermentation and pasteurization.  Louis Pasteur (1822 – 1895) Demonstrated that microbes are present in the air and can contaminate sterile solution, but that air itself does not creates microbe.  Louis Pasteur (1822 – 1895) Demonstrated that microorganisms are present in the air (1861) Condition Results Nutrient broth placed in a Microbial growth flask, heated and not sealed Nutrient broth placed in a No microbial growth flask, heated and sealed Spontaneous generation or biogenesis? Louis Pasteur’s experiment  Louis Pasteur (1822 – 1895) Next experiment Invented a “swan neck” flask in 1800 Filled the flask with broth, boil the broth and heated the flask neck to draw the broth up into the curve This trap microorganism in the neck of the jar, keeping the broth sterile Pasteur’s experiment disproving the spontaneous generation theory of microorganism  Louis Pasteur (1822 – 1895) His experiment ended the theory of spontaneous generation and form the basis for aseptic technique Louis Pasteur (1822 – 1895) Fermentation and Pasteurization Pasteur showed that microbes are responsible for fermentation Fermentation is the conversion of sugar to alcohol to beer or wine Microbial growth is also responsible for spoilage of food Bacteria that use alcohol and produce acetic acid spoil wine by turning it to vinegar (acetic acid)  Louis Pasteur (1822 – 1895) Fermentation and Pasteurization Pasteur demonstrated that these spoilage bacteria could be killed by heat. This application of a high heat for a short period of time is called pasteurization This prove that bacteria can cause infection Luis Pasteur promoted the ‘Germ Theory of disease’  Louis Pasteur (1822 – 1895) Among his important contribution include: 1. Microbial theory of fermentation. 2. Principles and practice of sterilization (steam sterilizer, hot air oven and autoclave. 3. Control of disease in silkworm. 4. Development of vaccines against: Anthrax Rabies 5.Discovery of streptococci. Robert Koch (1843-1910) A German doctor considered as father of bacteriology. Important contributions: 1. Discovery and use of solid media in microbiology. 2. Discover the causative agent of; Anthrax (1876) Tuberculosis (1882) Cholera (1883) Robert Koch (1843-1910) A German doctor considered as father of bacteriology Important contributions: 3. Koch’s phenomenon, hypersensitivity phenomenon of Mycobacterium tuberculosis. 4. Koch’s postulates(1884)  The Germ Theory Of Disease Koch’s postulates are as follows: The specific causative organism must be found in every case of the disease. The disease organism must be isolated in pure culture Inoculation of a culture into a healthy susceptible animal must produce the same disease The bacteria must be recoverable from the experimentally infected host  Koch’s postulates Koch’s postulates are used to prove the cause of an infectious disease (a specific microbe causes a specific disease)  Joseph Lister (1827-1912) English surgeon. Known as “father of aseptic surgery”. Promoted sanitary condition in the medical field. Used carbolic acid to clean instruments and bandages. Introduced antiseptic surgery. By spraying carbolic acid on surgical instrument, wounds and dressing, he reduce surgical mortality due to bacterial infection  The Germ Theory Of Disease Charles Chamberland Develop a porcelain filter to remove bacteria from the water – a collaborator of Pasteur Martinus Beijerinck (1851-1931) First person to study about virus Identify virus cause polio, chicken pox, hepatitis, haemophilus influenza type B  The Germ Theory Of Disease Ignaz Semmelweis (1818-1865) Obstetrician studied in Vienna Studied puerperal (childbed) fever Established that high maternal mortality was due to failure of doctors to wash hands after post-mortems Advocate hand washing to prevent transmission of puerperal fever from one OB patient to another Reduced maternal mortality by 90%  Paul Ehrlich Develop a “magic bullet” to kill specific bacteria without causing harm to the nearby human tissue Chemotherapy: the term for the use of chemical drugs to treat a specific disease, coined by Ehrlich in the late 1800 Discovered a drug name Salvarsan used to treat syphilis for nearly 40 years  The Birth Of Modern Chemotherapy Chemotherapy – treatments with chemicals Chemotherapeutic agents used to treat infectious disease can be synthetic drugs or antibiotics Antibiotics are chemicals produced by bacteria and fungi that inhibit or kill other microbes Quinine from tree bark has long been used to treat malaria  The Birth Of Modern Chemotherapy 1928: Alexander Fleming discovered the first antibiotic He observed that colonies of the bacterium staphylococcus aureus could be destroyed by the mold Penicillium notatum. He name the substance Penicillin 1940: Penicillin was tested and mass produced The Birth Of Modern Chemotherapy Dr Selman Waksman Discovered the second antibiotic streptomycin in 1949 – a major breakthrough for Tuberculosis treatment.  Immunological advances Edward Jenner (1749-1823) Made huge advances toward vaccine development Introduce first vaccine Develop small pox vaccination Used fluid from cow pox as immunization Inoculated a person with cow pox virus  Immunological advances Eli Metchnikoff Discovered phagocytes leading to the modern understanding of the immune system  Summary Microbiology means the study of microorganism too small to be seen with the naked eye Anton Van Leeuwenhoek known as Father of microbiology Francesco Redi experiment includes; filling a jar with decaying meat to disprove spontaneous generation Louis Pasteur invented a “swan neck” This application of a high heat for a short period of time is called pasteurization  Summary Robert Koch ; The first to cultivate anthrax bacteria outside Koch’s postulates are used to prove the cause of an infectious disease Joseph lister is a“father of aseptic surgery” Ignaz Semmelweis Advocate hand washing to prevent transmission of puerperal fever Alexander Fleming discovered the first antibiotic known as Penicillin Summary Alexander Fleming discovered the first antibiotic known s Penicillin Edward Jenner - Introduce first vaccine  MICROBIOLOGY & PARASITOLOGY RNB 10102 Topic 2: Common Terminology In Microbiology Learning Outcomes At the end of the session, student should be able to describe the common terminology used in microbiology  Common Terminologies Active Immunity An immunity develop from the production of antibodies by the immune system in response to the presence of an antigen Aerobe An organism that lives and grows in the presence of oxygen Anaerobe An organism that grows in the absence of oxygen Antibiotics Substances produced by the microorganisms that suppress the growth of other microorganisms and may eventually destroy them Antibody A protein that is produced in response to a specific antigen.  Common Terminologies Antigen Any substance that causes the immune system to produce antibodies against it Antimicrobial agent An agent active against microorganisms that may be produced either naturally or synthetically Antiseptic A chemical that destroys or inhibits the growth of microorganisms in or on living tissue Antiserum A serum containing antibodies against particular infectious agents Antitoxin An antibody against a particular toxin  Common Terminologies Aseptic Free from contamination caused by harmful bacteria, viruses or other microorganism Autoclave Sterilizer which operates at high temperature (in excess of 100⁰ C ) and pressure. Used in medical application to perform sterilization Bacteria Unicellular free-living organisms having both DNA and RNA Bacteraemia Circulation of bacteria in the blood Bacteriology Study of bacteria Biocide A chemical agent that inactivates microorganisms  Common Terminologies Biopsy A sample of tissue taken from the body in order to examine it more closely Capsule A viscid layer outside the cell wall seen in some bacteria and fungi Carrier One who harbours the infectious agent without suffering from any disease Chemoprophylaxis Administration of drugs to prevent disease Contagious disease Disease transmitted by direct contact  Common Terminologies Culture The process by which cells, tissue, microbial organism or viruses are grown under controlled condition Disease Infection which causes overt damage to the host Disinfectant A chemical that destroys or inhibits the growth of microorganism on inanimate objects or surfaces but not spores. Electrolyse A chemical which help to keep a correct water balance between the fluid in the cell and the surrounding medium Endemic disease A disease constantly presence in a particular area  Common Terminologies Endogenous Originated by the organism or factors already present in the patient’s body. Also implies infection from patient’s own flora Endotoxin A heat stable polysaccharides-protein-lipid complex which forms an integral part of the cell wall of gram-negative bacteria Epidemic A disease that spread rapidly involving many disease persons in an area at the same time Epidemiology Study of epidemic and their control Exogenous Originated by organism or factors from outside the patient’s body  Common Terminologies Exotoxin A heat labile protein which is secreted by certain species of bacteria and which diffuses rapidly into the surrounding medium Fomites Inanimate objects such as towels, pencils which may be contaminated by a pathogen from one person and act as a vehicle for its transmission to another Fungi Eukaryotes that may be unicellular or multicellular. They divide asexually, sexually or by both processes Gene A unit of inheritance found on chromosomes Immunity Resistance exhibited by the host to infection  Common Terminologies Gram-negative Organisms that stain pink by Gram’s method organism Gram-positive Organisms that stain violets by Gram’s method organism Haemolysis Breakdown of red blood cells with the release of haemoglobin Immune response Development of resistance to a foreign substance (e.g. infectious agent). It can be antibody-mediated (humoral), cell-mediated (cellular) or both Immunoglobulin A glycoprotein that function as antibody Incubation period Period between infection and appearance of first symptom  Common Terminologies Infection The invasion of body by pathogenic microorganisms and their multiplication which can lead to tissue damage and disease. Morbidity A disease condition or state. Mortality Loss of life or death. Motile Capable of movement. Mycology Study of fungus. Nosocomial Infection that is acquired in the hospital and infection other healthcare facilities and was not present or incubating at the time of patient’s admission.  Common Terminologies Nucleus An essential component of the cell that bears hereditary characters Outbreak Sudden eruption of disease/sudden increase in isolation rate of a particular pathogen Oxidation It is a process when oxygen combine with an element, changing the appearance of the element Pandemic A world wide epidemic Parasite Defined as an organisms that live on or in other living organism called the host to get food and shelter and cause disease.  Common Terminologies Passive Resistance that is transmitted to an immunity individual in a ready made form Pathogen A microorganism capable of producing disease pH The symbol that indicate the acidity or alkalinity of a medium. A pH less than 7 is acidic, pH more than 7 is alkaline and pH 7 is neutral Pigment A coloured substance Purulent Containing or discharging pus Pus Tick yellowish liquid produce from infected tissue, containing phagocytes  Common Terminologies Quantify To determine quantity Rash Skin eruption in spots or patches Room Usually between 22⁰ C to 25⁰ C temperature Septic Characterized by the presence of pathogenic microbes in the living tissue Septicaemia A condition characterize by the formation of toxic product by the circulating bacteria in the blood Serological Antigen-antibody reactions in vitro reactions  Common Terminologies Spore A resting cell that are highly resistance to desiccation, heat and chemical agent Sterile Free of life of every kind Sterilization A physical or chemical process that completely destroys microbial life including spores Tissue culture A method employ for the cultivation of viruses. It is of three types, organ culture, explant culture and cell culture (that include cell lines) Toxoid A toxin of pathogenic organism treated so as to destroys its toxicity but leave it capable  Common Terminologies Unicellular Single cell Vaccine An immunological substance designed to stimulate the body's own immune system to protect the person against subsequent infection or disease. Vaccination The process whereby a person is made immune or resistant to an infectious disease, by the administration of a vaccine.  Common Terminologies Unicellular Single cell Vectors An agent usually an insect that transmit an infection from one human host to another. such as mosquitos, ticks, lice, flies, flees and mites. Viable Able to live Viremia Presence of viruses in the blood Virulence Ability of a microbial strain to produce disease Yeast A unicellular fungus Zoonoses Infections disease transmit from animal to men  Microbiology & PARASITOLOGY RNB 10102 Topic 3: Classification of microorganism  Microorganism -introduction Live on communities called colonies Some microorganism capable of causing disease- referred too as pathogen Some microorganism are important for maintaining health and of have no harmful effect on the body – referred to as nonpathogen Colonies of nonpathogens in the body is known as normal flora Normal flora’s are not the same in all areas of the body (e.g. normal flora in the stomach is different from the skin) Non pathogen misplaced to other parts of the body can become pathogen (e.g. intestinal flora entering the bladder can cause urinary tract infection.  Learning Outcomes At the end of the session, student should be able to; define microorganism; differentiate between prokaryote cells and eukaryote cells; describe the different types of bacteria, virus and fungi discuss bacterial, viral and fungal in terms of their structure, function of different components; identify the disease cause by these major groups of microorganism.  Microorganism What is microorganism? Microorganism are organism or microbe too small to be seen with the naked eye. Where can you find microorganism? Found every where, both inside and outside the body Within the body Mouth Various body system Skin  Microorganism All living microorganisms, large and small have one thing in common, i.e.: the cell The cell is the structural unit of an organism that is classified as living and is sometimes called the building block of life. There are two types of cells: Eukaryotes Prokaryotes  Microorganism Prokaryotes Eukaryotes Definition Definition A unicellular organism that lacks a An organism that consists of one or membrane-bound nucleus. more cells each of which has a Prokaryotes include the bacteria nucleus and other well developed and cyanobacteria intracellular compartments Eukaryotes include all living organisms except bacteria, virus and certain (blue-green) algae Diagram of a Bacterial cells Diagram of a Eukaryotes  Prokaryotes and eukaryotes Characteristic Prokaryote Eukaryotes size Smaller: 1-10μm Larger:10-100μm Organization DNA is circular DNA is linear Lack a nucleus & Contain a nucleus, other membrane mitochondria, smooth bound organelles endoplasmic reticulum, rough endoplasmic reticulum, Golgi complex, lysosome  Prokaryotes and eukaryotes Characteristic Prokaryote Eukaryotes Method of Binary fission: the Mitosis: the nucleus divides division original of parent through four stages, cell splits to form prophase, metaphase, two cells, with the anaphase, and telophase and second daughter results in the formation of cell identical to the two new nuclei each having parent the same number of chromosomes as the parent nucleus  Prokaryotes and eukaryotes Characteristic Prokaryote Eukaryotes Cell wall Peptidoglycan Cellulose (in plant) (polysaccharides & Chitin ( in fungi) amino acid) Kingdom Bacteria Fungi Archaea Protozoa Alga  Classification of microorganism Classified according to size, structure and method of reproduction. Microorganism include: Bacteria Viruses Fungi Parasites (Protozoa) Mycoplasma Rickettsiae  Bacteria Description Single organism without the nucleus Bacterial cells are about 0.5 to 5.0 micrometres (μm) Either pathogenic or non-pathogenic Many produce toxin Bacteria are prokaryotes (means that they have no true nucleus) They have one chromosome of double-stranded DNA in a ring & reproduce by binary fission.  Bacteria Structures cells of bacteria Cell wall Cell membrane Cytoplasm Ribosome Chromosome Plasmid Flagella Capsule Pili Endospore  Bacteria cell structure Cell wall Consist of peptidoglycan also known as murein. Gram positives bacteria have a thick peptidoglycan layer in the cell wall; Gram negatives bacteria have a thin peptidoglycan layer and an outer membrane. Bacteria cell structure Cell wall Function Provides shape and structural support to the bacterium Give rigidity to bacterium Protect cells from bursting in hypotonic medium (Resists damage due to osmotic pressure) Bacteria cell structure Cell wall Function.. cont Protects from environmental factors. Contain receptors site for bacteriophage. Site of action of antibody.  Bacteria cell structure Cell membrane Also known as cytoplasmic membrane or plasma membrane Made up of protein, carbohydrate and lipid. Bacteria cell structure Cell membrane (cont…) Function Control movement of nutrients and waste in and out of cells Basic function is to protect the cell from its surroundings Acts as a semipermeable membrane which only allow selected material to move inside and outside the cells  Bacteria cell structure Cytoplasm Helps in cellular growth, metabolism and replication. Store houses of all the chemicals and components that are used to sustain the life of a bacterium.  Bacteria cell structure Ribosome A tiny granule made up of RNA and proteins Function Site of protein synthesis Free floating structures that helps in transferring the genetic code  Bacteria cell structure Chromosomal DNA Genetic material of the cell (DNA)  Bacteria cell structure Plasmid A small circle of DNA Bacterial cells has many plasmid Function Used to exchange DNA between bacterial cells  Bacteria cell structure Flagella Tail-like structure that projects from the cell body Organs of locomotion Function Responsible for motility Chemotaxis: (movement in response to a chemical) movement toward nutrients (positive chemotaxis), away from harmful chemical (negative chemotaxis)  Bacteria cell structure Capsule A kind of slime layer which covers the outside of the cell walls Composed of thick polysaccharide Function Protect cells from phagocytosis  Bacteria cell structure Pilli (also known as fimbriae) Thin, shorter, hair-like appendages that contain protein – pilin. Function: Allow bacteria to adhere to host tissue surface & to each other. Enables the cells to colonize. Enhances the bacteria’s ability to cause disease Sex pili are necessary for the transfer of plasmids DNA between bacteria.  Classification of bacteria Bacterial spores Some bacteria can grow spores when life-supporting condition are unfavourable Spores are thick capsules which the bacteria creates for self-protection Spores are highly resistant to extreme dryness, heat, freezing, radiation and action of toxic chemical Can lie dormant for years until condition are favourable for re- emergence Recap Bacterial Cell wall Consist of peptidoglycan Cell membrane control movement of nutrients and waste in and out of cells Flagellum responsible for motility Ribosome is the site for protein synthesis Capsule protect cells from phagocytosis Pilli allow adherence to host tissue surface & to each other  Classification of bacteria All microorganism have binomial nomenclature; First name indicates genus (group/class) Second name indicates species The genus name should begin with capital letter and the second name with small letters e.g. Staphylococcus aureus (Staphylococcus is the genus and aureus is the species name) or S.aureus Often immortalizes the person who discovered it or its origin e.g. Escherichia coli - Theodor Escherich coli - from colon  Classification of bacteria Bacteria are usually classified on the basis of their shapes. Broadly, they can be divided into: Sphere-shaped bacteria (Cocci) Rod-shaped bacteria (Bacilli) Spiral-shaped bacteria (Spirilla)  Classification of bacteria a. Cocci - Sphere-shaped bacteria. On the basis of arrangement they can be described as; Monococcus – appears single. Diplococci - appears in pairs Staphylococci - grape-like clusters Streptococci - appears in chains Tetrad – arranged in group of four  Sarcina – arranged in group of eight Arrangement of cocci  Classification of bacteria b. Bacilli Rod-shaped bacteria On the basis of arrangement they can be described as; Diplobacilli Streptobacilli Palisades Coccobacilli Arrangement of bacilli  Classification of bacteria c. Spirilla (or spirillum for a single cell) Curved bacteria which can range from a gently curved shape to a corkscrew-like spiral. Many spirilla are rigid and capable of movement. A special group of spirilla known as spirochetes are long, slender, and flexible.  Classification of bacteria Arrangement of Spiral Bacteria i. Vibrio ii. Spirilla Comma-shaped bacteria with less than one complete turn or twist Rigid spiral structure. Spirillum in the cell with many turns can superficially resemble spirochetes.  Classification of bacteria Arrangement of Spiral Bacteria iii. Spirochetes Have a helical shape and flexible bodies. Move by means of axial filaments.  identification of bacteria Can also be classified based on the results of staining. Staining of the bacteria forms the foremost and the most important step in the identification of bacteria. The isolated bacteria are stained by various methods depending upon the bacteria in focus.  identification of bacteria Methods of staining: 1. Gram staining - differentiates bacteria into two types i. Gram-positive - retain the stain (appear purple in colour) ii. Gram-negative – loosing the stain (appear pink or red in colour) Many gram-negative bacteria are more dangerous than gram-positive bacteria because they produce endotoxin that can cause haemorrhagic shock and severe diarrhoea  identification of bacteria Gram positive and Gram negative bacteria identification of bacteria Methods of staining: 2. Albert staining: to identify Corynebacterium diphtheriae. 3. Acid fast staining; Ziehl-Neelsen): is performed in cases suspected of Mycobacterial tuberculosis and mycobacterium leprae. Ziehl-Neelsen is used to diagnosed pulmonary tuberculosis – early morning sputum. identification of bacteria Methods of staining: 4. Simple staining 5. Negative staining 6. Differential staining  identification of bacteria Other method of identification is by: Chemical testing of bacteria grown in culture. To culture the bacteria, the infected body secretion is placed in a medium in which it can grow. Sensitivity test then perform to determine which antibiotic is most effective against the bacteria. Sensitivity test may also reveal drug resistant bacteria Common disease caused by bacteria Disease Treatment Boils, toxic shock Antibiotics, although Staphylococcus syndrome, most strains are not aureus. osteomyelitis, killed by penicillin. Methylene Resistant MRSA can only be Staphylococcus killed with one Aureus (MRSA), antibiotic vancomycin significant nosocomial and is not affected by infection. others. Common disease caused by bacteria Disease Treatment Strep throat, ear Antibiotics Streptococcus infections, scarlet group A (gram- fever, endocarditis positive coccus). can lead to rheumatic fever, heart valve damage. “Flesh – eating strep” is a rare strain causing necrotizing fasciitis that cause death. Common disease caused by bacteria Disease Treatment Neonatal infections, IV Antibiotics Streptococcus especially in group B (gram- premature birth, positive coccus). causing pneumonia, meningitis or septicaemia in newborns. Common disease caused by bacteria Disease Treatment Clostridium Gas gangrene in Amputation of perfringens (gram- contaminated wounds affected limb positive bacillus; – spore loves in dead spore- forming} tissue and produce toxins that destroy more tissue, so bacteria spreads, gas form bubbles in dead tissue. Common disease caused by bacteria Disease Treatment Clostridium difficile Severe diarrhoea; often Only 2 antibiotics (gram-positive develop with antibiotic will treat this: bacillus; spore- therapy and is called vancomycin and forming} pseudomembranous metronidazole enterocolitis, this is a (Flagyl) significant nosocomial infections Common disease caused by bacteria Disease Treatment Escherichia coli Normally found in the Antibiotics (gram-negative colon but can cause bacillus) infection if it enters the urinary tract or other parts of the body; common cause of nosocomial infection Common disease caused by bacteria Disease Treatment Escherichia coli Infection of colon casing Antibiotics, 0157:H7(gram- bloody diarrhoea and Dialysis for renal negative bacillus) kidney failure, known as failure haemolytic uremic “syndrome": can be fatal, often result from consuming undercooked ground meat. Common disease caused by bacteria Disease Treatment Mycobacterium tuberculosis Tuberculosis that destroy Antituberculosis (Bacillus) lung tissue, leaving large medications, such cavities; drug resistant as streptomycin strain are becoming more common. Infection caused by bacteria Disease Treatment Borrelia burgdorferi (spirochete) Lyme disease, spirochete Antibiotics transmitted by deer tick to human causing flu-like symptoms, irregular heartbeat, possible arthritis Common disease caused by bacteria Disease Treatment Rickettsia rickettsii (bacillus) Rocky mountain spotted Antibiotics fever spread by ticks; causes high fever, rash and pneumonia and can lead to death.  Common multidrug-resistant organisms (MDRO) Four most common multidrug-resistant organisms (MDRO) are: 1. Methicillin-resistant Staphylococcus aureus (MRSA) 2. Vancomycin-resistant Enterococcus (VRE) 3. Extended-spectrum beta-lactamase-producing (ESBL) 4. Clostridium difficile (C.diff) 5. Pseudomonas aeruginosa resistant to multiple antibiotics. recap Bacteria are usually classified on the basis of their shapes, need for oxygen and Gram-staining properties Bacteria that requires oxygen to grow is aerobic Bacteria that can grow in the absent of oxygen is anaerobic Staphylococci - grape-like clusters Streptococcus – appears in chain Diplococci – appears in pairs  Virus Description Virus come from a Latin word which means poison. A virus is a small infectious agent that replicates/reproduce only inside the living cells of other organisms.  Virus Description Smallest of the microbes Need an electron microscope to see them Virus are not whole cells, they depend on other living cells to provide food, nutrients and for production They are called obligate intracellular parasite because they can only grow and live inside another living cells Virus - Classification Fall into four broad groups a. Human and animal virus b. Plant virus c. Insect virus d. Bacterial virus Human viruses can be broadly classified as; a. Respiratory viruses b. Enteric viruses c. Arboviruses  Virus -sizes Virus vary in diameter from 20-300 nm (nanometer)  Virus - structure Composed of nucleic acids (RNA or DNA but not both) and a protein Lack rigid cell wall Have no mitochondria or other organelles Have an inner core of nucleic acid surrounded by a protein coat known as envelope Viruses that lack an envelop are called naked viruses The infectious virus particle is known as virion The capsid protect the nucleic acid from the environment Life cycle of Viruses Viral replication involves a series of steps: 1. Attachment 2. Penetration 3. Replication 4. Assembly 5. Release Life cycle of Viruses 1. Attachment (adsorption) First event in the infection of the cell is the attachment of virus to the specific receptors on the host cell wall. 2. Penetration Virus injects its genetic material (DNA or RNA) inside the host cell 3. Replication Virus DNA or RNA takes over the cell machinery and makes lots of copies of itself  Life cycle of Viruses 4. Assemble New virus components are assemble into mature viruses 5. Release The cell lysis and releases many new virus particles that can then infect other cells Life cycle of Viruses Replication of Viruses Common Diseases caused by virus Disease treatment Type 1 causes fever Antivirals such as Herpes blisters; acyclovir simplex Type 2 causes genital Herpesvirus 3 herpes; (varicella- Chicken contracted first, Antiviral: acyclovir zoster) then virus les dormant in nerve endings; if reactivated in adults, causes shingles that result in painful blisters along nerve pathways Common Diseases caused by virus Disease treatment Type 1 causes fever Antivirals such as Herpes blisters; acyclovir simplex Type 2 causes genital Herpesvirus 3 herpes; (varicella- Chicken pox contracted Antiviral: acyclovir zoster) first, then virus les dormant in nerve endings; if reactivated in adults, causes shingles that result in painful blisters along nerve pathways Common Diseases caused by virus Disease treatment Influenza “Flu” symptoms – aching Antiviral such as muscles, fever, Tamiflu and Relenza respiratory congestion, Prevention: annual flu cough immunization West Nile Virus found in birds and No antiviral exist – spread by mosquitos; supportive in causes headache and treatment confusion in some but may be asymptomatic in others  recap Smallest of the microbe can only be seen by electron microscope Virus are obligate intracellular parasite because they can only grow and live inside another living cells The infectious virus particle is known as virion  Fungi Description A fungus is a eukaryotic organism that is a member of the plant kingdom that contain no chlorophyll. Fungi reproduce my means of spores. Yeasts, molds and mushrooms are examples of fungi.  Fungi Many fungal species have long been used as a direct source of food, such as mushrooms and truffles and in fermentation of various food products, such as wine, beer, and soy sauce. More recently, fungi are being used as sources for antibiotics used in medicine. Many fungi produce bioactive compounds called mycotoxins that are toxic to animals including humans.  Fungi Yeasts A single-celled microorganisms reproduce by fission or budding that are capable of fermenting carbohydrates into alcohol and carbon dioxide. Yeast Beneficial yeast – Saccharomyces cerevisiae: used in baking and fermenting alcoholic beverages. Pathogenic yeasts – Candida albicans, C. tropicalis, C. stellatoidea, C. glabrata, ect  Fungi Fungal infection. Most fungi are not dangerous, but some types can be harmful to health. Can occur when the balance of normal flora is altered by antibiotic therapy 1. Mycoses Fungal infection in human Can be group under two heads: Superficial mycoses – include infection of the skin Deeper mycoses – include infections in the deeper tissue and visceral organ Fungi Fungal infection. 2. Dermatophytes A pathogenic fungus that grows on skin, mucous membranes, hair, nails, other body surfaces causing ringworm or tinea (most common is tinea pedis (athletic foot) 3. Candidiasis infection with candida, such as oral thrush and vaginitis.  Fungi Fungal infection. 4. Histoplasmosis In infection caused by breathing in spores of a fungus often found in bird and bat droppings. 5. Cryptococcosis Typically infects immunocompromised persons such as HIV. Cryptococcus is the most common life-threatening fungal infection in people with AIDS.  Common disease caused by fungi Disease Treatment Microsporum epidermophyton Ringworm, also known as tinea; can be Antifungals found on the skin or scalp; causes itchy red, round patches Athlete foot also caused by fungus Candida albicans Yeast infections; called thrush when found in Atifungals the mouth; often found in vagina and may result because antibiotics kill normal bacteria, allowing an overgrowth of yeast; can cause pneumonia and heart infections Recap Fungal infection in human is known as mycosis Fungal infection occurs when the balance of normal flora is altered by antibiotic therapy Most common fungal infection is vaginal candidiasis and athlete foot (tinea pedis) Algae – description Algae plant-like protists. Ranging from unicellular to multicellular forms. Mostly – non motile All algae have photosynthetic machinery ultimately – produce oxygen as a by-product of photosynthesis. Four main types of algae: Brown algae Red algae Green algae Blue-green algae also known as cyanobacteria  ALGAE – Disease Exposure to blue-green algae can cause rashes, skin and eye irritation, allergic reactions, gastrointestinal upset and other effects. Blue-green algae have the potential to cause a variety of adverse health effects, including liver toxicity (e.g., Microcystis aerugunosa) and neurotoxicity (e.g., Anabaena circinalis  RNB 10102: MICROBIOLOGY & PARASITOLGY TOPIC 4: GROWTH & REPRODUCTION OF MICROORGANISM GROWTH AND REPRODUCTION OF 1 MICROORGANISM  Learning Outcome After completing this session, student should be able to discuss the factors regulating the growth of microorganism; describe the growth curve of microorganism; describe the different methods of reproduction for bacteria, viruses and fungi. GROWTH AND REPRODUCTION OF SUMATHY 2 MICROORGANISM JANUARY 19 INTRODUCTION All living organism aim for ; i. Growth ii. Multiplication In order to achieve these aims, they essentially require proper nutrients, oxygen, pH and temperature. GROWTH AND REPRODUCTION OF SUMATHY 3 MICROORGANISM JANUARY 19 INTRODUCTION Microbial growth involves an increase in the number of cells rather than the size of individuals. During their growth cycles, microorganism goes through reproduction many times. A variety of factors affect the growth of microorganism. GROWTH AND REPRODUCTION OF SUMATHY 4 MICROORGANISM JANUARY 19 Factors Regulating Microbial Growth For their optimal growth bacteria require proper: 1. Nutrients 2. Moisture 3. Temperature 4. Gases: oxygen and air 5. pH or Acidity and alkalinity 6. Osmotic pressure 7. Light and radiation GROWTH AND REPRODUCTION OF SUMATHY 5 MICROORGANISM JANUARY 19  Factors Regulating Microbial Growth 1. Nutrients Certain basic nutrients are required for growth and maintenance of metabolic functions. Amount and type of nutrients depending on the microorganism. These nutrients include water, a source of energy, nitrogen, vitamins, and minerals. GROWTH AND REPRODUCTION OF SUMATHY 6 MICROORGANISM JANUARY 19 Factors Regulating Microbial Growth 1. Nutrients (…cont) Energy sources such as sugars, starch, protein, fats and other compounds provide the nutrients. Heterotrophs require organic materials for growth, e.g. proteins, carbohydrates, lipids as source of energy. All bacteria of medical importance belong to heterotrophs. A heterotroph is an organism that can't make its own food supply. GROWTH AND REPRODUCTION OF SUMATHY 7 MICROORGANISM JANUARY 19  Factors Regulating Microbial Growth 1. Nutrients (…cont) i. Carbon Use as energy sources Can be obtained from organic materials in the environment, or it may be derived from carbon dioxide. ii. Nitrogen use for the synthesis of proteins, amino acids, DNA, and RNA. Bacteria that obtain nitrogen directly from the atmosphere are called nitrogen-fixing bacteria. GROWTH AND REPRODUCTION OF SUMATHY 8 MICROORGANISM JANUARY 19  Factors Regulating Microbial Growth 1. Nutrients (…cont) ii. Phosphorus Use to make proteins, nucleic acids and vitamins. iii. Sulfur Used to form proteins and some vitamins (thiamin and biotin). iv. Vitamins required in small amount by certain bacteria as growth factors. GROWTH AND REPRODUCTION OF SUMATHY 9 MICROORGANISM JANUARY 19  Factors Regulating Bacterial Growth 1. Nutrients (…cont) v. Trace elements as iron, copper, and zinc are often used for the synthesis of enzymes. Most of the bacteria of medical importance will grow only if source of organic material such as nutrient is available. One can effectively promote or inhibit the growth of microorganism of interest is by controlling its physical and chemical environment. GROWTH AND REPRODUCTION OF SUMATHY 10 MICROORGANISM JANUARY 19  Factors Regulating Bacterial Growth 2. Moisture/water Use to dissolve the food they use for energy and growth. Water allows the food to get into the cells, is used for the many chemical reactions necessary for life and growth. Water also allows waste products to escape. Freezing, drying or salting are ways to reduce available water to bacteria and slow down their growth. GROWTH AND REPRODUCTION OF SUMATHY 11 MICROORGANISM JANUARY 19  Factors Regulating Bacterial Growth 3. Temperature Ideal temperature for growth varies between organism. Most flourish at normal body temperature of 37⁰C. Some prefer extremely cold or hot environment. Cold temperatures often slow the growth of microorganism which is the reason refrigeration is used to control bacterial growth in food. High temperatures usually kills most microorganism Steam sterilization and boiling are two most common method to kill pathogenic organism. GROWTH AND REPRODUCTION OF SUMATHY 12 MICROORGANISM JANUARY 19  Factors Regulating Bacterial Growth 3. Temperature (…cont) Usually classified according to the temperature at which they grow i. Psychrophiles (“cold loving” bacteria) Prefer cold temperatures of about 0°C to 20°C Optimum growth at 15°C ii. Psychrotrophs Capable of growing at 32°C to 45°C Cause spoilage of food stored under refrigeration e.g. bacteria: Yersinia and Listeria GROWTH AND REPRODUCTION OF SUMATHY 13 MICROORGANISM JANUARY 19  Factors Regulating Bacterial Growth 3. Temperature (…cont) iii. Mesophiles Optimum growth temperature: 25°C to 45°C Most human pathogens are mesophiles Grows well in human body whose normal temperature is around 37°C iv. Thermophiles (“heat loving”) Optimum temperature: 45°C to 70°C Commonly found in compose heaps, hot spring and water heaters GROWTH AND REPRODUCTION OF SUMATHY 14 MICROORGANISM JANUARY 19  Factors Regulating Bacterial Growth 4. Oxygen The need of oxygen for a particular bacterium reflects its mechanism. Can classify microorganism based on their oxygen requirements: i. Obligate aerobes ii. Obligate anaerobes iii. Facultative anaerobes iv. Microaerophiles v. Aerotolerant anaerobes GROWTH AND REPRODUCTION OF SUMATHY 15 MICROORGANISM JANUARY 19  Factors Regulating Bacterial Growth 4. Oxygen (…cont) ii. Anaerobic Bacteria (Anaerobes): Can grow only in the absence of free oxygen. They are destroyed by the presence of oxygen. They obtained their energy from fermentation reaction E.g.: Clostridium. GROWTH AND REPRODUCTION OF SUMATHY 16 MICROORGANISM JANUARY 19  Factors Regulating Bacterial Growth 4. Oxygen (…cont) i. Obligate aerobes Require oxygen to live Example: Pseudomonas, common nosocomial pathogen ii. Obligate anaerobes Cannot multiply in the presence of oxygen Often kill by traces of oxygen Examples Clostridium bacteria that cause tetanus and botulism. GROWTH AND REPRODUCTION OF MICROORGANISM SUMATHY JANUARY 19 17  Factors Regulating Bacterial Growth 4. Oxygen (..cont) iii. Facultative anaerobes Prefer oxygen, but can live without it Can grow both aerobically and anaerobically Aerobic respiration if oxygen is available Fermentation or anaerobic respiration if oxygen is absent Growth is greater in the presence of oxygen due to the production of more adenosine triphosphate (ATP) (energy source of cell) E.g. E. coli, Staphylococcus, yeasts, and many intestinal bacteria GROWTH AND REPRODUCTION OF SUMATHY 18 MICROORGANISM JANUARY 19  Factors Regulating Bacterial Growth 4. Oxygen (..cont) iv. Microaerophilic Bacteria (Microaerophiles): Require oxygen, but at low concentrations Poisoned by high concentrations of oxygen. Examples: Streptococcus, Lactobacillus, Campylobacter. v. Aerotolerant anaerobes Do not use oxygen but can tolerate it. Example: Lactobacillus carries out fermentation regardless of oxygen presence GROWTH AND REPRODUCTION OF SUMATHY 19 MICROORGANISM JANUARY 19 GROWTH AND REPRODUCTION OF SUMATHY 20 MICROORGANISM JANUARY 19  Factors Regulating Bacterial Growth 4. oxygen (..cont) Representative Anaerobic Pathogens 1. Clostridium tetani Agent of tetanus, puncture wounds Produces a toxin which enters the spinal column and blocks the inhibitory spinal motor neurons. Produces generalized muscle spasms or spastic paralysis. The muscle of the jaw are often the first affected, hence the name LOCKJAW. GROWTH AND REPRODUCTION OF SUMATHY 21 MICROORGANISM JANUARY 19 GROWTH AND REPRODUCTION OF SUMATHY 22 MICROORGANISM JANUARY 19  Factors Regulating Bacterial Growth 4. Oxygen (..cont) Representative of Anaerobic Pathogens. 2. Clostridium botulinum This soil organism is the causative agent of botulism which typically occurs after eating home canned alkaline vegetables which were not heated enough during canning. The neurotoxin blocks transmission across neuromuscular junctions and this results in flaccid paralysis. GROWTH AND REPRODUCTION OF SUMATHY 23 MICROORGANISM JANUARY 19 GROWTH AND REPRODUCTION OF SUMATHY 24 MICROORGANISM JANUARY 19 Factors Regulating Bacterial Growth 4. Oxygen (..cont) Representative Anaerobic Pathogens. 3. Clostridium perfringes and Clostridium sporogenes These organisms are associated with invasive infections known as Gas gangrene. 4. Clostridium difficile The causative agent of pseudomembranous colitis, a side effect of antibiotic treatment which eliminates the normal flora. GROWTH AND REPRODUCTION OF SUMATHY 25 MICROORGANISM JANUARY 19 GROWTH AND REPRODUCTION OF SUMATHY 26 MICROORGANISM JANUARY 19  Factors Regulating Bacterial Growth 4. Oxygen (..cont) The Streptococci – Microaerophiles 1. Group A Streptococcus - Streptococcus pyogenes A beta hemolytic organism - also bacitracin sensitive. Causes strep throat, rheumatic fever, glomerulonephritis and scarlet fever. GROWTH AND REPRODUCTION OF SUMATHY 27 MICROORGANISM JANUARY 19  Factors Regulating Bacterial Growth 4. Oxygen (..cont) The Streptococci – Microaerophiles 2. Group D Streptococcus - Enterococcus - Streptococcus faecalis A normal inhabitant of the large intestine. Frequent cause of bladder infections 3. Streptococcus pneumoniae. A normal inhabitant of the respiratory tract. Frequent cause of pneumonia in people who have been compromised by other illness. GROWTH AND REPRODUCTION OF SUMATHY 28 MICROORGANISM JANUARY 19  Factors Regulating Bacterial Growth 5. pH The term” pH” refers to the acidity or alkalinity of a solution Molds and yeast grow in wider pH range, but prefer pH between 5 and 6. Acidity inhibits most microbial growth and is used frequently for food preservation (e.g.: pickling). Alkalinity inhibits microbial growth, but not commonly used for food preservation. Acidic products of bacterial metabolism interfere with growth. Buffers can be used to stabilize pH GROWTH AND REPRODUCTION OF SUMATHY 29 MICROORGANISM JANUARY 19  Factors Regulating Bacterial Growth 5. pH (…cont) Organisms can be classified as: i. Acidophiles “Acid loving”. Grow at very low pH (0.1 to 5.4) Lactobacillus produces lactic acid, tolerates mild acidity. ii. Neutrophiles Grow at pH 5.4 to 8.5. (grows well in the body) Includes most human pathogens. GROWTH AND REPRODUCTION OF SUMATHY 30 MICROORGANISM JANUARY 19  Factors Regulating Bacterial Growth 5. pH (…cont) iii. Alkaliphiles “Alkali loving”. Grow at alkaline or high pH (7 to 12 or higher) Vibrio cholerae and Alkaligenes faecalis optimal pH 9. Soil bacterium Agrobacterium grows at pH 12 GROWTH AND REPRODUCTION OF SUMATHY 31 MICROORGANISM JANUARY 19 Factors Regulating Bacterial Growth 6. Salt Salt concentration is the major contributor to the osmotic effect of ions on growth Bacteria requires ion that are provided by salts and able to tolerate moderate salt concentration High salt or high sugar in the environment leads to loss of water from cells and ultimately to death GROWTH AND REPRODUCTION OF SUMATHY 32 MICROORGANISM JANUARY 19  Factors Regulating Bacterial Growth GROWTH AND REPRODUCTION OF SUMATHY 33 MICROORGANISM JANUARY 19 Factors Regulating Bacterial Growth GROWTH AND REPRODUCTION OF SUMATHY 34 MICROORGANISM JANUARY 19  Factors Regulating Bacterial Growth 6. Salt (…cont) However, some bacteria can adopt to high salt environment and is known as Halophiles. E.g. fungi, protozoa Halophiles have the mechanism to actively pump salt out, keeping the cell at a normal salt concentration GROWTH AND REPRODUCTION OF SUMATHY 35 MICROORGANISM JANUARY 19 MICROORGANISM REPRODUCTION Bacteria reproduce by:  Binary fission Viruses: Lysogenic cycle Lytic cycle Fungi: sporulation Sexual & asexual GROWTH AND REPRODUCTION OF SUMATHY 36 MICROORGANISM JANUARY 19  Bacterial Reproduction Whenever adequate nutrition and conducive environmental factors is available bacterium enlarges and eventually divides by binary fission. Generation time (Time required for a cell to divide, and its population to double) varies considerably: E. coli : every 20 minutes. Mostly : every 1 to 3 hours. Mycobacterium tuberculosis: every 24 hours to divide GROWTH AND REPRODUCTION OF SUMATHY 37 MICROORGANISM JANUARY 19  Bacterial Reproduction Binary fission (“division in half”) A type of cell division in which a parent cell copies it’s genetic material, and then divides, transforming into two daughter cells. GROWTH AND REPRODUCTION OF SUMATHY 38 MICROORGANISM JANUARY 19 Binary fission GROWTH AND REPRODUCTION OF SUMATHY 39 MICROORGANISM JANUARY 19  Bacterial Growth Curve The growth curve indicates multiplication and death of bacteria. Number of bacteria in the culture at different periods may be : 1. Total count - includes both living and dead bacteria 2. Viable count- includes only the living bacteria GROWTH AND REPRODUCTION OF SUMATHY 40 MICROORGANISM JANUARY 19  Bacterial Growth Curve When a bacterium is inoculated in a medium, it passes through four growth phases. GROWTH AND REPRODUCTION OF SUMATHY 41 MICROORGANISM JANUARY 19  Bacterial Growth Curve The pattern of growth include: 1. Lag Phase 2. Exponential (or log) Phase 3. Stationary Phase 4. Death Phase GROWTH AND REPRODUCTION OF SUMATHY 42 MICROORGANISM JANUARY 19  Bacterial Growth Curve 1. Lag Phase: Period of adjustment to new conditions. Little or no cell division occurs, population size doesn’t increase. Phase of intense metabolic activity, in which individual organisms grow in size. May last from one hour to several days Antibiotics have little effect at this stage GROWTH AND REPRODUCTION OF SUMATHY 43 MICROORGANISM JANUARY 19  Bacterial Growth Curve 2. Exponential (or log) Phase Cells begin to divide and generation time reaches a constant minimum. Period of most rapid growth. Cells are at highest metabolic activity. Cells are most susceptible to adverse environmental factors at this stage. Radiation Antibiotics GROWTH AND REPRODUCTION OF SUMATHY 44 MICROORGANISM JANUARY 19  Bacterial Growth Curve 3. Stationary Phase: Population size begins to stabilize. Overall cell number does not increase. Cell division begins to slow down. Factors that slow down microbial growth: Accumulation of toxic waste materials Acidic pH of media Limited nutrients Insufficient oxygen supply Endospores would form now GROWTH AND REPRODUCTION OF SUMATHY 45 MICROORGANISM JANUARY 19  Bacterial Growth Curve 4. Decline or Death Phase: Population size begins to decrease. Number of cells dying more than the number of cells produced. Cells lose their ability to divide. A few cells may remain alive for a long period of time. GROWTH AND REPRODUCTION OF SUMATHY 46 MICROORGANISM JANUARY 19 Culture medium A nutrient material prepared for the growth o f microorganisms in a laboratory is called a culture medium. Culturing of microorganism requires an appropriate growth medium. Material contain all nutrients required for the desired organism to grow. Can be liquid or solid (i.e. solid agar) Must be initially sterile (i.e.no living organism) Growth should only occur following inoculation of the medium during desired organism. GROWTH AND REPRODUCTION OF SUMATHY 47 MICROORGANISM JANUARY 19 GROWTH AND REPRODUCTION OF SUMATHY 48 MICROORGANISM JANUARY 19  Recap Bacteria reproduce by binary fission Four phases if bacterial growth: Lag phase: cells adjust to medium before dividing Log phase: exponential growth Stationary phase: growth = death (wastes, lack of nutrients) Death phase: poor environment results in death > growth GROWTH AND REPRODUCTION OF SUMATHY 49 MICROORGANISM JANUARY 19 Viral Reproduction Replicate either by lytic cycles or lysogenic cycle. The difference is that: The cells dies at the end of the lytic cycle The cell remains alive in the lysogenic cycle – remain dormant Refer previous notes on lytic life cycle of a virus. GROWTH AND REPRODUCTION OF SUMATHY 50 MICROORGANISM JANUARY 19 Viral lytic cycle GROWTH AND REPRODUCTION OF SUMATHY 51 MICROORGANISM JANUARY 19  Viral Reproduction Lysogenic cycle Some virus such as herpes and HIV enter the host cell but remain dormant for years without destroying the host cell. The viral DNA is incorporated into the host chromosome known as prophage At some point, the viral DNA becomes active, produces new viruses and destroy the host cell as the new viruses are released. GROWTH AND REPRODUCTION OF SUMATHY 52 MICROORGANISM JANUARY 19  Viral Reproduction Lysogenic cycle 1. Attachment Virus attach to cell 2. Penetration or entry Insert DNA into host cells 3. Integration Viral DNA integrate into the host chromosome 4. Replication Host cell and viral DNA replicate and divide –remain in dormant state Under certain condition- become lytic. GROWTH AND REPRODUCTION OF SUMATHY 53 MICROORGANISM JANUARY 19 Lytic and lysogenic cycle GROWTH AND REPRODUCTION OF SUMATHY 54 MICROORGANISM JANUARY 19 GROWTH AND REPRODUCTION OF SUMATHY 55 MICROORGANISM JANUARY 19 GROWTH AND REPRODUCTION OF SUMATHY 56 MICROORGANISM JANUARY 19  Fungal Reproduction Fungi reproduce both asexually and sexually but always produce spores as reproductive cells. Spores are usually dispersed by air currents, and germinate in suitable conditions. GROWTH AND REPRODUCTION OF SUMATHY 57 MICROORGANISM JANUARY 19  Fungal Reproduction Haploid hyphae, found below the soil, fuse to begin reproduction. The hyphae enlarge, break through the soil as white spheres called buttons. Buttons grow and mature, forming a stalk and a spherical cap. Within the cap, gills form, consisting of many tangled, modified hyphae. Specialized extensions from gills containing two haploid nuclei of different parents fuse, then undergo meiosis to produce four haploid spores, which are released over several days. GROWTH AND REPRODUCTION OF SUMATHY 58 MICROORGANISM JANUARY 19 GROWTH AND REPRODUCTION OF SUMATHY 59 MICROORGANISM JANUARY 19 After completing this lesson, the student should be able to:  differentiate common terminology related to infectious disease  differentiate types of infections  define the stages of infection process  define the inflammation  discuss the cardinal sign of inflammation  state the purpose of inflammation  discuss the clinical manifestation of systemic infection  Microorganism exist everywhere and most of them are harmless, and some are even beneficial in that they perform essential function in the body  Infection occurs when an organism is able to colonize and multiply within the host Asepsis  Freedom from disease-causing microorganisms Colonization  It is the process when microorganism become resident flora where they grow and multiply but do not cause disease Contamination  Presence of microorganism on the body surface or an inanimate object Infectious disease  The pathologic events that result from the invasion and multiplication of microorganisms in a host Sepsis  Presence of bacteria or other infectious organism or their toxins in the blood or in other tissue of the body Pathogen  Microorganism that are capable of causing diseases Phagocytosis  The engulfing of microorganisms and foreign particles by phagocytes Virulence  Degree to which microorganism can cause infection in the host or invade the host Definition : An invasion and multiplication in body tissue by microorganisms that cause cellular injury.  Some microorganism are normal resident flora in one part of the body, yet produce infection in another. E.g, Escherichia coli - normal inhabitant of the large intestine but a common cause of infection of the urinary tract  The process of infection begins with transmission of infectious organism  Infection may end in infectious disease, a condition that depends on the response of the host to the invader Infectious disease are classified according to their severity, duration and the extent throughout the body  Local infection ❑ It is an infection where the pathogens that invade are limited to a specific point of body and remain there, multiplying until eliminated ❑ The sign and symptom are vary depending on the system affected  Systemic infection ❑ It is a condition where pathogens spread and damage different parts of the body ❑ E.g; measles and chickenpox - the virus initially invade the upper respiratory tract and then spread to the skin causing a rash and skin vesicle An infection can be acute or chronic depending on the severity and duration of symptoms  Acute infection ❑ Appear suddenly or last a short time such as influenza  Chronic infection ❑ Occur slowly, over a long period, and may last months or years ❑ Example tuberculosis, hepatitis C, syphilis  Latent infectious disease ❑ Arises from microorganisms that remain dormant in the body for long period, but then become active (usually when the person is experiencing physical and psychological stress) ❑ E.g; the herpes virus which causes cold sores and the chickenpox virus that may re-emerge later in life causing shingles  Opportunistic infection ❑ Arises from microorganisms which are not normally pathogenic to healthy people ❑ The harmless microorganisms may become pathogenic to those whose immune system has been compromised  Primary infection  The initial infection caused by microorganisms in host  Reinfection  The subsequent infection by same organism in the same host  Secondary infection  New infection set up by the new organism in the host when resistance of the host is lowered due to pre-existing infections disease  Cross-infection  This when a patient is suffering from a disease and a new infection is set up from another host or external source  Nosocomial  Cross infection occurring in the hospital or hospital acquired infection  Subclinical  Is one where clinical symptom are not apparent. There are 4 stages:  Incubation  Prodromal  Illness  Convalescence 1. Incubation  It is the time interval between entry of an infectious agent in the host and the onset of the symptoms  At this time, the infectious agent invades the tissue and begins to multiply to produce an infection and highly contagious to others  During this period there are no sign and symptoms  Example : Common cold 1-2 days, Influenza 1- 3 days, Tetanus 2-21 days 2. Prodromal  It is the time interval from the onset of nonspecific symptoms until specific symptoms of the infectious process begin to manifest  The infectious agent continues to invade & multiply  The patient may also be infectious to others  Early signs and symptoms are present but are vague, e.g. fatigue, or malaise, mild fever 3. Illness  The illness period, or acute phase, is when sign and symptom of the disease are present, e.g. fever, muscle pains, photophobia, sore throat 4. Convalescence  As the patient’s immune response and other defense mechanisms overcome the pathogen, the person gradually regains strength and health is usually restored  Sometimes the convalescence period can be lengthy and, although the individual recover from the illness, permanent damage can be caused by destruction of tissues in the affected area. E.g. deafness may follow middle ear infection System affected Sign and symptoms Skin Inflammation: redness, pain, swelling and heat Respiratory tract Increased secretion, cough, sore throat, dyspnoea Urinary tract Dysuria, frequency, urgency, cloudy and fishy smell of urine Gastrointestinal Abdominal pain, nausea, vomiting, diarrhea, tract poor appetite Central nervous Confusion, drowsiness, stiff neck, headache, system intolerance of light (photophobia) Definition : It is a local and nonspecific defensive response of the tissues to an injurious or infectious agent.  It is an immediate response of the body to any kind of injury to its cells and tissue  The response can be induce by any mechanical, chemical or infectious disease – produce factor that injures cells of the body  Commonly, words with the suffix –itis describe an inflammatory process  Example, appendicitis – inflammation of appendix; gastritis – inflammation of the stomach Purpose:  Neutralize and destroy harmful agents  Limit their spread to other tissue in the body  Prepare the damaged tissue for repair 5 classic sign of inflammation  Pain – from tissue swelling and chemical irritation of nerve endings  Swelling – due to accumulated fluids at the site  Redness – caused by increased blood flow to the injured area  Heat – due to hyperemia (increase of blood supply)  Impaired function of the part  Definition - it is an infection in which the pathogen is distributed throughout different part of the body rather than concentrated in one area  It can be life-threatening and serious infections with other complications can result in serious tissue damage if left untreated.  Usually cause by bacteria or virus  Main characteristic of infection: Affects the bloodstream causing symptoms throughout the body Pathogen is distributed throughout the body, rather than being concentrated in one area Bacterial toxin is the major reason that leads to systemic infection  Most common e.g. of a systemic infection are cold, influenza Clinical manifestation Malaise  Common symptom  Feel tired and lack of energy  Sleep more than usual …Clinical manifestation Fever  Fever is the common sign  Lead to decrease in appetite, dehydration and headache, increase heart rate …Clinical manifestation Chills  Triggers by systemic infection  Cause shiver …Clinical manifestation Aches  Ache to the fore head and back  In extreme cases, the patient will experience the whole body ache …Clinical manifestation Nausea  Systemic infection triggers a feeling of nausea  The person reacts to certain smells by vomiting …Clinical manifestation Vomiting  It is one of the major symptoms of systemic infection  The person would have the tendency of vomiting, even after consuming regular food Antibiotic  Substances produced by the microorganisms that suppress the growth of other microorganisms and may eventually destroy them. Spectrum of activity of antibiotics Antimicrobial agent is categorized into:  Broad spectrum Depending on their activity against a range of gram-  Narrow spectrum positive and gram-negative bacteria. E.g. - Broad spectrum antibiotics are active against many gram-positive and gram-negative bacteria. Narrow-spectrum antibiotics effective only against gram-negative bacteria Mode of action  Inhibitors of cell wall synthesis,  Inhibitors of cell membrane function,  Inhibitors of protein synthesis,  Inhibitors of nucleic acid synthesis,  Inhibitors of other metabolic processes,  Only few antiviral drugs have been develop.  Antibacterial drugs are not effective against viruses.  Viruses are intracellular, in order to attack them, chemotherapy agent must enter host cells. This needs a high degree of selective toxicity.  Not many antifungal drugs.  Two well known antifungal drugs include:  Nystatin ✓ Produce during fermentation by Streptomyces noursei ✓ Antimicrobial activity is limited to yeast and fungi.  Griseofulvin ✓ Obtained from Penicillium griseofulvum ✓ Use in the treatment of many superficial fungi infection of the skin and body and also some systemic mycosis  Bacteria may acquire resistance to drugs. Factors contributing to the evolution of resistant microbial organism:  Over prescription of antibiotics  Use of inappropriate antibiotics for infecting organism  Incomplete use of antibiotics prescription as symptom subside  Harbouring and spreading of resistant organism by carriers  Increased of antibiotic in farming, thus contaminating milk and meat Ways to minimize drug resistance  Avoid indiscriminate use of antibiotics when they are no real clinical use.  Avoid use of antibiotics commonly use of generalized infections.  Using correct dose of proper antibiotic to overcome infection quickly.  Using combination of antibiotic of proven effectiveness.  Use a different antibiotic when an organism gives evidence of becoming resistance to one used initially. What is asepsis?  Freedom from disease-causing microorganisms What is infection?  An invasion and growth of microorganisms in the body tissue What is local infection?  Infection with pathogen limited in one area and multiplying until eliminated In the inflammation process, the redness and heat of an inflamed area are due to a local hyperemia caused by  vasodilation What is the type of infection where pathogen spread and damage different parts of the body?  Systemic infection What is inflammation?  Local and nonspecific defensive response of the tissues to an injurious or infectious agent What is the clinical manifestation of inflammation?  Pain, heat, redness, swelling & impaired function of the part What is the clinical manifestation of systemic infection?  Malaise, fever, chills, aches, nausea, vomiting After completion of the lesson, the student will be able to:  define infection  describe the agent causing infection  explain the sources of infection: ❑ endogenous ❑ exogenous  describe the link in the chain of infection  discuss the way of breaking the chain of infection Asepsis  It is a state of being free from living pathogenic microorganisms that are capable of causing diseases Cross-contamination  Transmission of infectious micro-organisms from one person or object to another Infection  An invasion of body tissue by microorganisms and their growth there Infectious disease  Refers to the pathologic events that result from the invasion and multiplication of microorganisms in a host Sterilization  Process of destroying all micro-organisms and pathogen Virulence  Degree to which microorganism can cause infection in the host or invade the host  Biological agent – living organisms that invade the host. E.g.; Bacteria, Virus, Fungi, Parasites  Chemical agent - substances that can interact with the body. E.g.; food additives, medications & industrial chemicals  Physical agent – factor in the environment that are capable of causing disease. E.g.; heat, light, noise, radiation & machinery Biological agent  Living organisms that invade the host such as: bacteria, virus, fungi, protozoa and parasite 1. Bacteria  Single cell microorganism capable of causing disease in humans  Most common infection causing microorganism  All are capable of reducing organ function by invading tissue and cause inflammation  Can be transmitted through food, air, water, soil, vectors or sexual activity 1. Bacteria (…cont)  Some of the most deadly diseases and devastating epidemics in human history have been caused by bacteria, including:  Cholera  Diphtheria  Dysentery  Plague  Pneumonia  Tuberculosis  Typhoid  Typhus Infections Causative organism Brain (bacterial Streptococcus pneumoniae, Neisseria, meningitis) meningitides, Haemuphilus influenzae, Streptococcus agalictaiae, Listeria monocytogenes Ear (otitis media ) Streptococcus pneumoniae Pneumonia Commonly acquired - Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus. Atypical - Mycoplasma pneumoniae, Chlamydia pneumoniae, Legionella pneumophila Tuberculosis - Mycobacterium tuberculosis Infections Causative organism Upper respiratory Streptococcus pyogenes, tract infection Haemophilus influenzae Gastritis Helicobacter pylori Food poisoning Campylobacter jejuni, Salmonella, Shigella, Clostridium, Staphylococcus aureus, Escherichia coli Eye infections Staphylococcus aureus, Neisseria gonorrheae, Chlamydia trachoma Sinusitis Streptococcus pneumoniae, Haemophilus influenzae Multidrug-resistant microorganism include:  Methicillin-resistant staphylococcus aureus (MRSA) can cause a variety of problems ranging from skin infections and sepsis to pneumonia to bloodstream infections (septicaemia).  Vancomycin-resistant enterococci (VRE) 2. Virus  Invades host, attaches to a cell, enter and release genetic material (DNA or RNA).  This genetic material helps the virus multiply; takes control of the cell, reproduce more new virus which is then release and infect new cells.  Not all viruses destroy their host cell.  Sometimes lies dormant in a cell; and reactivate years later making the host ill e.g. varicella- zoster virus.  Viruses may target skin cells and cause warts. 2. Virus (…cont)  An individual may become infected by:  inhaling the virus  bitten by infected insects or animal  through sexual contact  Respiratory infections of the upper airways, nose and throat are the most common forms of viral infections.  Some antiviral medications may help, either reduce the virus' ability to reproduce, or boost the patient's immune system. 3. Fungi  Tiny primitive organisms feeding on living plants, animals and decaying organic material.  Reproduce by spores which people either inhale or pick up on their skin.  Infection caused by fungi is known as mycosis.  Systemic mycoses due to primary or opportunistic pathogens;  a primary pathogen causes disease because of its presence in a healthy human,  an opportunistic pathogen causes disease in a host with a weakened immune system. 3. Fungi  Patient at risk to develop fungal infection include:  On long-term strong antibiotics  HIV/AIDS  Receiving chemotherapy  Uncontrolled diabetes  Example of diseases cause by fungi are ringworm (tinea), candidiasis. 4. Protozoa  Single celled organisms.  Reproduce by binary fission.  Live in a wide variety of moist habitats including fresh water, marine environments and the soil.  Can be free-living or parasitic in nature.  Infections range from asymptomatic to life threatening, depending on the species and strain of the parasite and the resistance of the host. 4. Protozoa (…cont)  Transmission can occurs;  through a faecal-oral route (for e.g., contaminated food or water or person-to- person contact) - Entamoeba histolytica causes amoebiasis.  to other humans by an arthropod vector (for e.g., through the bite of a mosquito or sand fly)- Plasmodium (some of which cause malaria) 5. Helminth  Can be free-living or parasitic in nature.  They are large, multicellular organisms  E.g. Flukes (Trematodes)  Tapeworms (Cestodes)  Roundworms (Nematodes)  Transmitted from hand to mouth  Cause infection in the gastrointestinal tract Can be divided into two main group:  Endogenous  Exogenous From individual’s own body → own normal flora  Resident: ❑ Always present in the body ❑ Benefits (if they remain in the site with which they associated)  Prevent the overgrowth of harmful microorganisms by competing for attachment & nutrients.  Some synthesize vitamins that are absorbed as nutrients by the host (e.g. Vit K & B12).  Some produce substances that inhibit pathogenic species.  Benefits (if they remain in the site with which they associated)  Stimulate the development of certain tissues, e.g. colon and lymphatic tissues in gastrointestinal tract.  Stimulate production of cross-reactive antibodies.  If they turn up at a site with which they are not normally associated. E.g.; staphylococcus aureus is normal in upper respiratory tract but if goes to the lower tract will cause pneumonia  Transient flora ❑ Survive on skin less than 24 hours ❑ Easily removed with soap and water ❑ Acquired during contacts with contaminated areas mouth, nose, perineal area, genitals, anal area  Examples of normal Flora in human Area of body Commensal organism Mouth & Bacteria: Staphylococci, Streptococcus teeth mutans, Yeast: Candida Throat Bacteria: Streptococci pneumoniae, Neisseria species, Haemophilus influenzae Skin Bacteria: Staphylococci, Streptococcus, Cornynebacterium Bowel Bacteria: Escherichia coli, Enterobacteriacea, Enterococci, Clostridium species Vagina Bacteria: lactobacilli, Staphylococci (adult) Yeast: Candida  An individual’s immunity against own normal flora becomes compromised when there is:  Contamination during surgery  Malnutrition  Impairment of blood supply  Debilitating diseases such as AIDS, diabetes or any other accompanying infection  Caused by organism not normally present in the body but which have gained entrance from the environment  Source include: 1. Human ❑ From sexually transmitted organism: - treponema pallidum causes syphilis - N.gonorrhea causes gonorrheal infection ❑ Exposure to blood and other body fluids – by needle stick injuries, mucous membrane, and skin exposure - hepatitis B and C - human immunodeficiency virus (HIV) Gonorrheal infection to the baby … Source include 2. Animal/vector  Zika virus - spread to people through the bite of infected mosquitoes.  Rabies – spread through bite of infected dog or wild animal and broken skin causes acute encephalitis (inflammation of the brain)  Anthrax – spread through handling infected animals or other materials containing anthrax spores, eating infected meat or breathing in spores.  Avian influenza (bird flu)- through direct or close contact with infected poultry Rabies … Source include 2. Animal/vector  Salmonella bacteria – from animal product such as raw meat, unpasteurized milk, and raw eggs can cause food poisoning. … Source include 3. Water  Can be a major source of infection especially when in contact with sewage  Waterborne disease – transmitted by consumption of infected water  Common microorganism – protozoa and bacteria which can cause diarrhea … Source include 4. Food  May contaminated during processing, handling with contaminated hands or tools  Good environment for bacterial or any other pathogen to multiply and produce toxin  Bacteria cause food poisoning – salmonella, E. coli, campylobacter, listeria  Shigella can cause dysentry (severe diarrhea) 5. Environment include soil and air  Soil can be contaminated with human faeces that contain several pathogenic organism which have sporing capabilities enabling them to survive harsh environments such as:  Clostridium tetani – causes tetanus  Clostridium botulinum – causing food poisoning 5. Environment include soil and air  Air can be contaminated with organism shed from the skin or respiratory tract such as:  Meningococci  Measles  Haemophilus influenza  Mumps  Corynebacterium diphtheria which causes diphtheria What are the agent causing infections & give example?  Biological (bacteria, virus, fungi, parasites), The microorganism that only can grow and replicate in living cell is called Virus  The organisms that comes from own body is known as Endogenous  The organism that gain entrance from environment is known as Exogenous What is the agent causing infections that spread by contaminated food with human & animal feces?  Protozoa What is the agent causing infection that causes ringworm?  Fungi  1 2 6 3 5 4 What is the chain of infection?  It is a model used to understand the infection process  The information is needed to interrupt or prevent an epidemic  The spread of infectious disease follows a well- known sequence of events of six links  Each cycle of links represents step in transmission of infection  All the six elements need to be present and linked to each other in order for an infection to be able to spread  It is the microorganisms that can cause infection or disease  Infectious agent are: ❑ Bacteria 1 ❑ Viruses ❑ Fungi ❑ Parasites ❖ Protozoa ❖ Helminths  The place where organisms can lives and reproduce such as: 2 ❑ People ❑ Animals ❑ Inanimate objects ❑ environment  The route by which the infectious agent leaves one host and travel to another  Common route: 1. Skin & mucosa – when there is open 3 wound. A wound can be an entry point and portal of exit. ….Common route 2. Gastrointestinal tract –feces may transport the typhoid from infected person  Common route for bacteria or viruses to escape an infected host  Common infection – hepatitis A, salmonella species  Through: ❑ Mouth – saliva, vomitus ❑ Anus – Faeces, ostomies 3. Genitourinary tract – through urethral meatus, urinary diversion ….Common route 4. Respiratory tract  Released by nose or mouth through sneezing, coughing, breathing or talking  Common infectious disease- measles, mumps, pulmonary tuberculosis & influenza...Common route 5. Blood  Through: ❑ Open wound ❑ Needle puncture site ❑ Any disruption of intact skin or mucous membrane surface  Common infectious disease - Hepatitis B,C, HIV...Common route 6. Reproductive tract  Through: ❑ Vagina – vaginal discharge ❑ Urinary meatus – semen, urine  Common infectious disease – gonorrhea, syphilis, Herpes simplex, Hepatitis B  The way the microorganism is transported to a new host. Mode of transmission include;  Contact transmission – direct and indirect  Airborne transmission  Vehicle transmission  Vector transmission 4  1. Contact transmission includes: a. Direct b. indirect a. Direct contact transmission  Agents is transmitted by physical contact between two individuals – person to person contact, e.g.  Touching  Kissing,  Sexual intercourse  Droplets sprays a. Direct contact transmission e.g. … cont.  Touching an infected individual. Contaminated hands are one of the most common source of direct transmission  Kissing,  Sexual intercourse  Droplets sprays from sneezes, cough, spitting, singing  Mother to child during pregnancy, breast feeding or birth b. Indirect contact transmission  Involves inanimate objects called fomites that become contaminated by pathogens from an infected individual or reservoir;  Indirect source include:  Door knobs, handrails  Tables, beds, chairs  Washroom surfaces  Cups, dishes, cutlery, trays  Medical instruments  Pens, pencils, phones, office supplies 2. Airborne transmission  Generated through droplets in sneezing, coughing or talking  Droplets can also be generated during certain medical procedures, such as bronchoscopy  These droplets travel through the air and are inhaled through the respiratory system or absorbed through mucous membrane- eye, nose, or mouth  E.g. :Tuberculosis, Chickenpox, Measles 3. Vehicle-borne transmission  It is any substance act as transporter/medium to introduce an infectious agent into a susceptible host. Such medium include:  Water  Food  Air – pathogens are carried on droplets nuclei in dust for a distance greater than 1 meter 4. Vector-borne transmission  Vectors are living organisms that can transmit infectious diseases between humans or from animals to humans  Transmission occur by injecting salivary fluid during biting or depositing feces or other materials on the skin through bite wound or traumatized skin area  Examples of vector are flies, mites, fleas, tick  The most common vector for disease is the mosquito which can transmit malaria and dengue  Are the doorways or pathways into the host  Usually, microorganisms enter the body of the host by the same route they used to 5 leave the source.  Respiratory tract – by  Gastrointestinal tract- inhaling contaminated by ingesting particles or droplet contaminated food or water  Genitourinary-  Broken skin – bites, through contamination cuts, punctures, with infected vaginal abrasions and burns secretion or semen  Transplants – blood, organs  Transplacental – mother to unborn child  A susceptible host is any person who is at risk for infection  A compromised host is a person at increased risk and more likely 6 than others to get infection  Impairment of the body’s natural defenses and a number of other factors can affect susceptibility to infection Level of susceptibility depends upon:  Age ❑ The very young and the very old are usually more susceptible to diseases than older children and young adults ❑ Congenital infection during gestation ❑ Neonatal infection occur in 1st 28 days of life due to maybe mother’s vaginal flora, or direct/indirect transmission from hospital staff.  Gender ❑ Due to anatomical differences – urinary infection common in female than male  Stress ❑ Prolonged physical or emotional stress alters body’s hormonal balance and reducing resistanc