HES 032 Review Micropara Final Term Review October 14, 2024 PDF

MICROPARA FINAL TERM REVIEW (October 14, 2024 | 5-8 pm) HES 032: Microbiology and Parasitology 1st semester, AY 2024-2025 HISTORY OF MICROBIOLOGY SCIENTISTS AND THEIR KEY CONTRIBUTIONS PIONEERS IN MICROBIOLOGY Anton van Leeuwenhoek (1632–1723) “Father of Microbiology” “Father of Bacteriology” “Father of Protozoology” He observed various tiny living creatures, which he called “animalcules.” PIONEERS IN MICROBIOLOGY Louis Pasteur (1822–1895) Alcoholic Fermentation Anaerobic growth Pasteurization Germ Theory of a Disease Development of the early vaccines PIONEERS IN MICROBIOLOGY Robert Koch (1843–1910) Koch’s Postulates B. anthracis produces spores, capable of resisting adverse conditions. Koch developed methods of cultivating bacteria on solid media. PIONEERS IN MICROBIOLOGY Robert Koch (1843–1910) M. tuberculosis and Vibrio cholerae Tuberculin PPD CONTRIBUTORS IN MICROBIOLOGY Robert Hooke (1665) Published a book, entitled Micrographia Coined the microorganisms as “cells” CONTRIBUTORS IN MICROBIOLOGY Edward Jenner (1796-1800s) Coined the term, “immunity” Smallpox vaccine CONTRIBUTORS IN MICROBIOLOGY Selman Waksman (1942-1944) Streptomycin Coined the term, “antibiotic” SIGNIFICANT CONTRIBUTORS Alexander Fleming (1881–1955): Penicillin Martinus Beijerinck (1851–1931): Discovery of viruses Paul Ehrlich (1854–1915): “Magic Bullet” model Lazzaro Spallanzani (1729–1799): Food spoilage CELL THEORY AND BIOGENESIS CELL THEORY German botanist Matthias Schleiden and German zoologist Theodor Schwann The theory stating that all living organisms are composed of cells. HISTORICAL DEVELOPMENT 1. Robert Hooke (1665) 2. Antonie van Leeuwenhoek (1674) 3. Matthias Schleiden (1838) and Theodor Schwann (1839) 4. Rudolf Virchow (1855) THEORY OF ABIOGENESIS A.k.a “Theory of Spontaneous Generation” Life can arise spontaneously from nonliving material THEORY OF BIOGENESIS Rudolf Virchow (1858) Biogenesis directly opposed the earlier theory of spontaneous generation (abiogenesis) The theory states that "life comes from life" BINOMIAL NOMENCLATURE AND TAXONOMY TAXONOMY Refers to the science of classiﬁcation of living organisms. ○ Classiﬁcation is the arrangement of organisms into taxonomic groups (known as taxa [singular: taxon]) on the basis of similarities or relationships. Taxa include kingdoms or domains, divisions or phyla, classes, orders, families, genera, and species. Let us take Staphylococcus aureus (a bacteria) for example. Domain: Bacteria Phylum: Bacillota Class: Bacilli Order: Bacilliales Family: Staphylococcaceae Genus: Staphylococcus Species: S. aureus NOMENCLATURE Nomenclature is the assignment of names to the various taxa according to international rules. Nomenclature of bacteria is named after the binomial nomenclature. ○ Identiﬁcation is the process of determining whether an isolate belongs to one of the established, named taxa or represents a previously unidentiﬁed species. NOMENCLATURE RULES The name of a taxon between subclass and genus is formed by the addition of the appropriate suﬃx to the stem of the name of the type genus. A bacterium's species name consists of two parts: the genus name, which indicates the group it belongs to, and the species epithet, which, when combined with the genus name, makes the bacterium’s name unique. NOMENCLATURE RULES The genus name and the species epithet form together the scientiﬁc name of the species, which is always written in italics. ○ The ﬁrst letter of the genus should always be capitalized, whereas the ﬁrst letter species epithet should be written in lowercase. Trivial names are often used as a simpliﬁed way of naming a bacterial genus. A trivial name should neither be written with capital ﬁrst letter nor in italic. NOMENCLATURE RULES The abbreviation “sp.” is used to designate a single species, whereas the abbreviation “spp.” is used to designate more than one species. If misunderstandings cannot occur, you can abbreviate the genus name after it has been written for the ﬁrst time in a text, e.g. M. bovis. However, note that there are also bacteria called Mycoplasmopsis bovis and Mycobacterium bovis. NOMENCLATURE RULES Nicknames and slang terms frequently used within hospitals are: ○ GC and gonococci (for Neisseria gonorrhoeae) ○ Meningococci (for N. meningitidis) ○ Pneumococci (for S. pneumoniae) ○ Staph (for Staphylococcus or staphylococcal) ○ Strep (for Streptococcus or streptococcal). Genus: Pseudomonas Species: P. aeruginosa MICROBIAL CHARACTERISTICS An organism’s complete collection of genes is referred to as the organism’s genotype or genome. An organism’s complete collection of physical characteristics is known as the organism’s phenotype. SPOT CHECK! The science of classiﬁcation of living organisms. TAXONOMY The assignment of names to the various taxa according to international rules. NOMENCLATURE SPOT CHECK! Arrange the order of taxonomy. Order Kingdom Class Domain Family Species Genus Phylum SPOT CHECK! [TRUE OR FALSE] A trivial name should be written in italics. FALSE There is no need to italicize nicknames and slang terms. TRUE The ﬁrst letter of the species epithet should be capitalized. FALSE The appropriate suﬃx for the FAMILY rank is -aceae. TRUE Does the slang term “strep” refer to Streptococcus pneumoniae? FALSE BACTERIAL CELL STRUCTURE AND MORPHOLOGY Cellular Microbes: Bacteria & Archaea Bacteria & Archaea Unicellular and lack nucleus Found everywhere there is moisture Reproduce asexually Bacteria Bacteria. Cell walls contain peptidoglycan (some lack a cell wall) Archaea. Cell walls composed of polymers Archaea Bacteria Classifying Bacteria 1. MORPHOLOGY & ARRANGEMENT Bacteria Criteria for Classifying Bacteria 1. MORPHOLOGY & ARRANGEMENT Bacteria Criteria for Classifying Bacteria 2. STAINING REACTION Gram positive: Blue to purple Gram negative: Pink to red Bacteria Criteria for Classifying Bacteria Bacteria Criteria for Classifying Bacteria Bacteria Criteria for Classifying Bacteria Bacteria Criteria for Classifying Bacteria 3. MOTILITY Associated with the presence DISTINCT MOTILITY OF VARIOUS of flagella or axial filaments BACTERIA Tumbling: Listeria monocytogenes Gliding: Capnocytophagia Darting: Campylobacter spp. Cork screw: Spirochetes Twitching: Ringella spp. Shooting star: Vibrio cholerae Bacteria Criteria for Classifying Bacteria 4. GROWTH IN CULTURE MEDIA Nutritional Requirements: Colony Morphology: Shape, Margin, Hemolysin, vitamins, minerals, X- and Elevation, Size. Texture, Appearance, V-Factor, salts, etc. Pigmentation and Optical property Bacteria Criteria for Classifying Bacteria 4. ATMOSPHERIC REQUIREMENTS Aerobes: 21% O2 + 0.02% CO2 Anaerobes: 0% O2 + 5-10%H2 + 90% N2 Capnophiles: 5-10% CO2 + 5 O2 Microaerophiles: 5-10% O2 + 8-10% CO2 + 80%N2 Bacteria Criteria for Classifying Bacteria 5. BIOCHEMICAL & METABOLIC ACTIVITIES Bacteria Criteria for Classifying Bacteria 6. PATHOGENICITY Property leading to disease production; presence of virulence factors & toxins Bacteria Criteria for Classifying Bacteria 6. PATHOGENICITY Hemolysin is an example of toxin produce by a bacteria. Bacteria Criteria for Classifying Bacteria 7. Genetic Composition Bacteria Archaea Archaea Prokaryotes that are closely related to eukaryotes Many are extremophiles which means that they live in extreme environmental conditions Methanogens are archaea that can produce methane. Archaea Microbial Diversity: Eukaryotic Microbes Cellular Microbes: Eukaryotic Microbes Protozoa Unicellular, mostly free-living organisms and are animal-like Some protozoa are parasites Protozoa Classification of Protozoa based on Locomotion Amebae Move by cytoplasmic extensions called pseudopodia Protozoa Classification of Protozoa based on Locomotion Ciliates Move by hair-like cilia on their surfaces Protozoa Classification of Protozoa based on Locomotion Flagellates Move by whip-like flagella Protozoa Classification of Protozoa based on Locomotion Sporozoa Non-motile but has apical complex for attachment Protozoa Cellular Microbes: Eukaryotic Microbes Fungi Includes yeast, moulds & mushrooms Saprophytes; garbage disposers of nature Fungal cell walls contain chitin Hyphae: microscopic unit of fungi Mycelium: intertwining structure composed of tubular filaments Fungi YEAST MOULD Unicellular Multicellular Reproduce asexually Filamentous by budding Colonies are fluffy, Colonies are moist cottony, wooly or creamy, opaque & powdery pasty Grows at room Grows at physiologic temperature temperature Fungi Fungal Reproduction Sexual Fungi exhibiting sexual reproduction are called perfect fungi Ex: Ascospores, Asexual Basidiospores, Oospores, Fungi exhibiting asexual Zygospores reproduction are called imperfect fungi Ex: Sporangiospores, Conidia or arthrospores Fungi Botanical Taxonomy Zygomycota Basidiomycota Asexual reproduction Considered as plant by sporangiospores pathogen Sexual reproduction by Sexual reproduction by zygospores basidiosphores Ascomycota Deuteromycota Asexual reproduction Most medically by conidia important fungi Sexual reproduction by Asexual reproduction ascospores by conidia Fungi Types of Mycoses Superficial Involves the outer epithelial layers of skin, & top layers of the hair & nails Ex: Piedra, Tinea Cutaneous versicolor, Tinea nigra Involves deeper layers palmaris of the skin and more tissue Ex: Tinea capitis, ringworm, jock itch Fungi Types of Mycoses Subcutaneous Gain entry into the subcutaneous tissue via trauma of the skin Systemic Ex: Chromoblastomycoses, Often acquires via Madura foot inhalation & disseminate to various organ systems Ex: North American blastomycosis, Desert fever, Histoplasmosis Fungi Types of Mycoses Deep Opportunistic Fungi rarely cause disease in healthy individuals, but they can cause disease in individuals with medical conditions Ex: Candidiasis, Cryptococcosis BACTERIAL POPULATION GROWTH CURVE Factors that aﬀect Microbial Growth Availability of nutrients- necessary for energy sources Moisture- cells are composed of 70-90% water Temperature- microorganisms have optimal minimum and maximum growth temperature. Most pathogens grow best at normal body temperature (37C) pH- acidophiles prefer acidic environments wherein alkaliphiles prefer alkaline environments Diﬀerent pH level of organ system and body ﬂuids Skin 4-5.5 Stomach 1.5-3.5 Intestine 6-7.4 Liver 7- 7.2 Urine 4.6-8.0 Take away terms: Thermophiles- organisms that thrive in high temperatures Halophiles- organisms that thrive in high salt concentration Psychrophiles- group of organisms who have the ability to grow and reproduce in low temperatures Factors that prevent the GI from bacterial colonization Presence of digestive enzymes Acidic pH of the stomach Alkaline pH of the intestines Bacterial Growth Curve Consist of four phases: Lag Phase - newly inoculated bacteria are adopting to new environment. The bacteria at this time are absorbing nutrients, synthesizing enzymes and preparing for cell dvision Exponential or Log Phase- cells are dividing by binary ﬁssion and doubling in numbers in each generation time Stationary Phase- period of equilibrium wherein microbial death balances the number of new cells Death Phase- shortage of available nutrients causing death rate > reproductive rate ANTIMICROBIAL AGENTS CHAPTER 9 Inhibiting the growth of pathogens in Vivo using antimicrobial agents An antimicrobial agent is any chemical (drug) used to treat an infectious disease, either by inhibiting or by killing pathogens in vivo. Drugs used to treat bacterial diseases are called antibacterial agents, whereas those used to treat fungal diseases are called antifungal agents. Drugs used to treat protozoal diseases are called antiprotozoal agents, and those used to treat viral diseases are called antiviral agents. How antimicrobial agents work To be acceptable, an antimicrobial agent must inhibit or destroy/kill the pathogen without damaging the host. The ﬁve most common mechanisms of action of antimicrobial agents are as follows: Inhibition of cell wall synthesis Damage to cell membranes Inhibition of nucleic acid synthesis (either DNA or RNA synthesis) Inhibition of protein synthesis Inhibition of enzyme activity TAKE AWAY: 1944, Selman Waksman and his colleagues isolated streptomycin (the ﬁrst antituberculosis drug) and subsequently discovered antibiotics such as chloramphenicol, tetracycline, and erythromycin in soil samples. It was Waksman who ﬁrst used the term “antibiotic.” Antibacterial agents Sulfonamides- inhibit the production of folic acid in bacteria that need p-aminobenzoic acid to synthesize folic acid. Without folic acid, bacteria cannot produce certain essential proteins and ﬁnally die. Sulfa drugs are bacteriostatic, meaning that they inhibit growth of bacteria (as opposed to a bactericidal agent, which kills bacteria). Antibacterial agents Penicillins- are referred to as B-lactam drugs due to the presence of B-lactam ring, penicillin interferes with the synthesis and cross-linking of peptidoglycan, a component of bacterial cell walls. Cephalosporins- The cephalosporins are also β-lactam antibiotics and, like penicillin, are produced by moulds. Also like penicillins, cephalosporins interfere with cell wall synthesis and are bactericidal. Antibacterial agents Carbapenems- They target the cell envelope and have excellent activity against a broad spectrum of bacteria, including many aerobic Gram-positive bacteria, most aerobic Gram-negative bacteria, and most anaerobes. Glycopeptides including vancomycin target the cell envelope. Antibacterial agents Tetracyclines- are broad-spectrum drugs that exert their eﬀect by targeting bacterial ribosomes thus inhibiting bacterial protein sythesis. They are bacteriostatic. Aminoglycosides -are bactericidal broad-spectrum drugs that inhibit bacterial protein synthesis. Antibacterial agents Macrolides- Macrolides inhibit protein synthesis. They are considered bacteriostatic at lower doses and bactericidal at higher doses. Fluoroquinolones are bactericidal drugs that inhibit DNA synthesis Polymyxin- most eﬀective against Gram Negative Bacteria due to its ability to disrupt the outer membrane Antibacterial agents (Multidrug Therapy) In some cases, a single antimicrobial agent is not suﬃcient to destroy all the pathogens that develop during the course of a disease; thus, two or more drugs may be used simultaneously to kill all the pathogens. In tuberculosis, for example, in which multidrug-resistant strains of Mycobacterium tuberculosis are frequently encountered, four drugs (isoniazid, rifampin, pyrazinamide, and ethambutol) are routinely prescribed, and as many as 12 drugs may be required for especially resistant strains. HISTORICAL TAKE AWAY: Robert Koch a german physician and microbiologist discovered and described TB bacterium Antifungal Agents Mechanism By binding with cell membrane sterols (e.g., nystatin and amphotericin B) By interfering with sterol synthesis (e.g., clotrimazole and miconazole) By blocking mitosis or nucleic acid synthesis (e.g., griseofulvin and 5-ﬂucytosine) TAKE AWAY: It is much more difficult to use antimicrobial drugs against fungal and protozoal pathogens, because they are eukaryotic cells.Thus, antifungal and antiprotozoal tend to be more toxic to the patient. Antiprotozoal Agents Antiprotozoal drugs are usually quite toxic to the host and work by (a) interfering with DNA and RNA synthesis or (b) interfering with protozoal metabolism Antiviral Agents Antiviral agents are particularly diﬃcult to develop and use because viruses are produced within host cells. They are referred to as acellular microbes because they are not considered living organisms. The ﬁrst antiviral agent eﬀective against human immunodeﬁciency virus (HIV) (the causative agent of acquired immune deﬁciency syndrome or acquired immunodeﬁciency syndrome [AIDS])—zidovudine (also known as azidothymidine [AZT])—was introduced in 1987 MICROBIAL GROWTH INHIBITION IN VITRO CHAPTER 8 Deﬁnition of Terms Sterilization involves the destruction or elimination of all microbes, including cells, spores, and viruses. When something is sterile, it is devoid of microbial life. Disinfection- describes the elimination of most or all pathogens (except bacterial spores) from nonliving objects. Use of Physical Methods to Inhibit Microbial Growth Heat- most practical, eﬃcient, and inexpensive method of sterilization of those inanimate objects and materials that can withstand high temperatures. Because of these advantages, it is the means most frequently used. Two factors—temperature and time—determine the eﬀectiveness of heat for sterilization. Use of Physical Methods to Inhibit Microbial Growth The thermal death point (TDP) of any particular species of microorganism is the lowest temperature that will kill all the organisms in a standardized pure culture within a speciﬁed period. The thermal death time (TDT) is the length of time necessary to sterilize a pure culture at a speciﬁed temperature. Use of Physical Methods to Inhibit Microbial Growth ❖ Dry Heat- king in a thermostatically controlled oven provides eﬀective sterilization of metals, glassware, some powders, oils, and waxes. These items must be baked at 160° to 165°C for 2 hours or at 170° to 180°C for 1 hour ❖ Moist Heat- t applied in the presence of moisture, as in boiling or steaming. The vegetative forms of most pathogens are quite easily destroyed by boiling for 30 minutes. Use of Physical Methods to Inhibit Microbial Growth ❖ An autoclave is like a large metal pressure cooker that uses steam under pressure to completely destroy all microbial life. The increased pressure raises the temperature above the temperature of boiling water (i.e., greater than 100°C), and forces the steam into the materials being sterilized. ❖ Done at a pressure of 15 psi, at a temperature of 121.5° C, for 20 minutes. Use of Physical Methods to Inhibit Microbial Growth ❖ Cold- Most microorganisms are not killed by cold temperatures and freezing, but their metabolic activities are slowed, greatly inhibiting their growth. Refrigeration merely slows the growth of most microorganisms; it does not completely inhibit growth. ❖ Radiation- In practice, a UV lamp (often called a germicidal lamp) is useful for reducing the number of microorganisms in the air. Its main component is a low-pressure mercury vapor tube. Use of Chemical Agents to Inhibit Microbial Growth ❖ Disinfectants- Chemical disinfection refers to the use of chemical agents to inhibit the growth of pathogens, either temporarily or permanently ❖ Antiseptics- Most antimicrobial chemical agents are too irritating and destructive to be applied to mucous membranes and skin. Those that may be used safely on human tissues are called antiseptics. An antiseptic merely reduces the number of organisms on a surface; it does not penetrate pores and hair follicles to destroy microorganisms residing there. MICROSCOPY Microscope - Optical instrument - Tiny objects that cannot be seen with the unaided eye. - Resolving power or Resolution → “limit” Types of Microscopes ★ Simple Microscope - containing only one magnifying lens - Ex. Magnifying glass - Anton Van Leeuwenhoek - Max power x300 Leeuwenhoek’s microscopes. Types of Microscopes ★ Compound (light) Microscope - containing more than one magnifying lens a. Ocular lens (x10) b. Objective lenses (4x, 10x, 40x, 100x) - Hans Jansen & his son Zacharias - About 1000x magniﬁcation - “Photomicrographs” - Wavelength of visible light (app 0.45 um) a. Limits the size of objects Total Magniﬁcation Total Magniﬁcation = Objective Lens X Ocular Lens a. Scanning – 4x b. Low Power Objective (LPO) – 10x c. High Power Objective (HPO) – 40x d. Oil Immersion Objective (OIO) – 100x Most ocular lenses magnify specimens by a factor of 10. Parts of a Microscope EPIDEMIOLOGY OF DISEASES Epidemiology - study of factors that determine the frequency, distribution, and determinants of diseases in human populations, and ways to prevent, control, or eradicate diseases in populations. - Who? What? Where? When? Why? How? Epidemiologic Terminology: Infectious Disease - (infection) is a disease that is caused by a pathogen. Communicable disease - transmissible from one human to another (i.e., person to person) Contagious disease - a communicable disease that is easily transmitted from one person to another. All communicable diseases are infectious but not all are contagious Epidemiologic Terminology: Zoonotic Diseases - Infectious diseases that humans acquire from animal sources incidence - The number of new cases of that disease in a deﬁned population during a speciﬁc time period morbidity rate - the number of new cases of a particular disease that occurred during a speciﬁed time period per a speciﬁcally deﬁned population (usually per 1,000, 10,000, or 100,000 population) Epidemiologic Terminology: Sporadic diseases - a disease that occurs only occasionally (sporadically) within the population of a particular geographic area. Endemic diseases - are diseases that are always present within the population of a particular geographic area. Epidemic Diseases (outbreak) - a greater than usualnumber of cases of a disease in a particular region, usually occurring within a relatively short period of time. An epidemic does not necessarily involve a large number of people, although it might. Epidemiologic Terminology: Pandemic Diseases - a disease that is occurring in epidemic proportions in many countries simultaneously sometimes worldwide. Interactions between Pathogens, Hosts, and Environments 1. Factors pertaining to the pathogen: - Virulence - portal of entry - number of organisms Interactions between Pathogens, Hosts, and Environments 2. Factors pertaining to the host: - Health status - Nutritional status - Other factors aﬀecting susceptibility Interactions between Pathogens, Hosts, and Environments 3. Factors pertaining to the environment: - Physical factors - Reservoirs - Sanitary & housing conditions - Availability of potable water Chain of Infection Six components in the infectious disease process 1. a pathogen 2. a reservoir of infection 3. a portal of exit 4. a mode of transmission 5. a portal of entry 6. a susceptible host Reservoirs of Infection - any site where the pathogen can multiply or merely survive until it is transferred to a host - may be living hosts or inanimate objects or materials - Living reservoirs: humans, household pets, farm animals, wild animals, certain insects, and certain arachnids (ticks and mites). - Non-living reservoirs: Air, soil, dust, food, milk, water, and fomites. Epidemiologic Terminologies: carrier - person colonized with a particular pathogen, but the pathogen is not currently causing disease in that person. Passive carriers - carry the pathogen without ever having had the disease. incubatory carrier - a person who is capable of transmitting a pathogen during the incubation period of a particular infectious disease. Epidemiologic Terminologies: Convalescent carriers - harbor and can transmit a particular pathogen while recovering from an infectious disease Active carriers - carry the pathogen without ever having had the disease. Epidemiologic Terminologies: Zoonotic Diseases: - infectious diseases that humans acquire from animal sources - A variant form of Creutzfeldt Jakob (CJ) disease in humans, called variant CJ disease, may be acquired by ingestion of prion infected beef from cows with bovine spongiform encephalopathy (BSE or “mad cow disease”). Modes of Transmission: Droplet transmission - transfer of pathogens via infectious droplets (particles 5 μm in diameter or larger) - by coughing, sneezing, and even talking. Airborne transmission - dispersal of droplet nuclei, which are the residue of evaporated droplets, and are smaller than 5 μm in diameter. Modes of Transmission: Vehicular Transmission - involves contaminated inanimate objects (“vehicles”), such as food, water, dust, and fomites. - Vectors include various types of biting insects and arachnids. Contact Transmission - Infectious organisms may be transmitted by direct contact (i.e., skin-to-skin) or indirect contact (i.e., inanimate objects). PATHOGENESIS OF INFECTIOUS DISEASES Four Phases in the Course of an Infectious Disease 1. Incubation Period - between exposure to pathogen and onset of symptoms 2. Prodromal period - patient feels “out of sorts” but not experience actual symptoms of the disease 3. Period of illness - typical symptoms associated with that particular disease 4. Convalescent Period - Patient recovers Acute, Subacute & Chronic Disease Acute Disease - rapid onset, usually followed by rapid recovery Chronic Disease - has insidious onset, lasts a long time. Subacute Disease - occur more suddenly than chronic disease, but less sudden than acute disease Symptoms VS Signs of Disease Symptom of a Disease - perceived by the patient; Subjective a. Symptomatic Disease: the patient experiences symptoms b. Asymptomatic Disease: patient is unaware of because of absence of symptoms Signs of a Disease - Objective ﬁndings HOST DEFENSE MECHANISMS Nonspeciﬁc Host Defense Mechanisms Nonspeciﬁc Host Defense Mechanism I. First Line of Defense a. Physical Barriers - Skin & Mucous membrane b. Cellular & Chemical Factors Skin: Dryness, Acidity (pH ~5.0), Temperature (

HES 032 Review Micropara Final Term Review October 14, 2024 PDF

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