Bacterial Types and Their Characteristics

Microbiology & Parasitology - RNB 10102

• The modern science of microbiology began about 100 years ago.
• Microbiology is the study of micro-organisms too small to be seen with the naked eye.
• These include bacteria, algae, protozoa, fungi, and viruses.
• Only a small percentage of microorganisms are capable of causing disease (pathogenic).
• The majority of microorganisms help maintain the balance of life in our environment.

Learning Outcomes

• Students should be able to define microbiology.
• Identify the importance of microbes in our lives.
• Identify the contributions of individuals or scientists to microbiology.
• Discuss 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 word "microbiology" is derived from the Greek words "micros" (small), "bios" (life), and "logy" (study of).
• Microbiology is a branch of biology dealing with simple life forms, usually single-celled organisms, that are not visible to the naked eye.

History of Microbiology

• Anton Van Leeuwenhoek (1632-1723): Started the field of microbiology, used 300X magnification lenses to observe microorganisms.
• Robert Hooke (1665): Popularized the use of the compound microscope. Laid groundwork for cell theory.

Theory of Spontaneous Generation (1650-1850)

• Spontaneous generation theory: belief that some life forms arise spontaneously from non-living matter.
• Francesco Redi (1626-1697): Among the first to call into question spontaneous generation, performed experiments with decaying meat to disprove the idea.
• John Tyndall (1668-1859): Showed that "optically pure" air (extremely filtered) contains no microorganisms.

The Golden Age of Microbiology (1857-1914)

• Beginning with Pasteur's work, discoveries on the relationship between microbes and disease, immunity, and microbial drugs.

Louis Pasteur (1822-1895)

• Demonstrated that microbes are present in the air and can contaminate sterile solutions but that air itself does not create microbes.
• Performed experiments that disproved the theory of spontaneous generation.
• Invented the "swan neck" flask.
• Microbial fermentation and pasteurization.

Robert Koch (1843-1910)

• Contributed to the discovery and use of solid media in microbiology.
• Discovered the causative agents of anthrax, tuberculosis, and cholera.
• Developed Koch's Postulates (criteria for proving a specific microbe cause a particular disease).

The Germ Theory of Disease

• Koch's postulates
• The specific causative agent 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.

Microbiology Practical Application

• The study of microbiology helps nurses to understand how disease-producing microorganisms enter, exit, and spread through the body.
• Nurses must understand principles of disinfection and effects of drugs on microorganisms.
• Proper collection of specimens for bacteriological examination is important along with interpreting laboratory reports.

Microbiology - Summary

• Microbiology is a study of microorganisms.
• Key figures include Anton Van Leeuwenhoek and Robert Hooke.
• Key scientific theories include the germ theory of disease and Koch's postulates.
• Important applications include vaccination, hygiene, and antimicrobial treatment.

Common Terminologies in Microbiology

• Active Immunity: Immunity developed by producing antibodies in response to an antigen.
• Aerobe: Organism that grows in the presence of oxygen.
• Anaerobe: Organism that grows in the absence of oxygen.
• Antibiotic: Substance produced by microorganisms that inhibits growth of other microorganisms
• Antibody: Protein produced in response to a specific antigen.
• Antigen: Substance that causes an immune response.
• Antimicrobial agent: Agent that stops growth or destroys microorganisms.
• Antiseptic: Chemical that destroys or inhibits the growth of microorganisms on living tissue.
• Antiserum: Serum containing antibiotics against a particular infectious agent.
• Antitoxin: Antibody against a particular toxin.
• Aseptic: Free from contamination.
• Autoclave: Sterilizer that uses steam under pressure.
• Bacteria: Unicellular prokaryotic organisms.
• Bacteraemia: Bacteria present in the blood.
• Bacteriology: Study of bacteria.
• Biocide: Chemical agent to kill or destroy microorganisms.
• Biopsy: Tissue sample for examination.
• Capsule: Viscous layer outside the cell wall (found in some bacteria and fungi).
• Carrier: Person who harbours a pathogen but doesn't develop illness.
• Chemoprophylaxis: Administration of drugs to prevent a disease.
• Contagious disease: Disease spread by direct contact.
• Culture: Process of growing cells, tissues, etc. under controlled conditions.
• Disease: Infection with a particular agent causes harm to the body.
• Disinfectant: Chemical that kills microorganisms but not necessarily the spores.
• Electrolysis: chemical that balances the water balance between the cell and surrounding medium.
• Endemic disease: Disease constantly present in particular area.
• Endogenous: Originated from within the body.
• Endotoxin: Heat-stable toxic substance found in the outer membrane of gram-negative bacteria cells.
• Epidemic disease: Rapidly spreading disease in an area.
• Epidemiology: Study of epidemics.
• Exogenous: Originated from outside the body.
• Exotoxin: Heat-labile protein secreted by certain bacteria
• Fomites: Inanimate objects that carry pathogens.
• Fungi: Eukaryotic organisms.
• Gene: Unit of inheritance
• Immunity: Resistance to an infectious disease.
• Incubation period: Time between infection and symptoms
• Infection: Invasion of body tissue by a pathogen.
• Morbidity: Disease conditions or state.
• Mortality: Loss of life or death.
• Motile: Capable of movement
• Mycology: Study of fungi.
• Nosocomial infection: Acquired in a hospital or healthcare facility environment
• Nucleus: Essential component of the cell containing genetic material.
• Outbreak: Sudden increase in a disease.
• Oxidation: Chemical process combining oxygen with another element.
• Pandemic: Worldwide epidemic.
• Parasite: Organism that benefits by living on or in another organism.
• Pathogen: Organism that causes disease.
• Phagocytosis: Engulfing process by phagocytes.
• Pigment: Colored substance
• Purulent: Containing pus
• Pus: Yellowish fluid.
• Passive immunity: Immunity mediated via antibodies acquired from outside the body
• Positive chemotaxis: Movement toward a stimuli
• Prodromal period: Time between the onset of non specific symptoms and the onset of specific symptoms.
• Prokaryotes: Unicellular organism that do not have a membrane bound nucleus.
• Prokaryote, eukaryotes: Classification according to whether cells have a nucleus or not
• Portal of entry: Doorways into the body
• Portal of exit: Route by which a pathogen leaves the body
• Reservoir: Place where pathogens live and thrive
• Rash: Eruption of the skin in spots or patches
• Redness: Increased blood flow to an injured area
• Room temperature: Usually between 22°C and 25°C
• Sepsis: Presence of bacteria or other infectious agent or their toxins in the blood or other body tissue
• Septicaemia: Blood poisoning
• Serological reactions: Antigen-antibody reactions in vitro
• Spore: Resting cell of a microorganism that is highly resistant to external factors.
• Sterile: Free from harmful organisms
• Sterilization: Process of destroying microorganisms and pathogens
• Species: Group of similar organisms
• Spirilla: Spiral shaped bacteria
• Sputum: Mucous from the lungs
• Stationary phase: Phase in bacterial growth where the rate of cell division = cell death
• Stress: Prolonged physical or emotional stress
• Symptom: Feeling or manifestation of a disease or disorder
• Systemic infection: Pathogen spreads and damages different parts of the body.
• Taxonomy: Classification of organisms on hierarchical levels
• Temperature: Ideal for growth varies among organisms
• Tissues culture: Cultivating virus, tissues etc. in a petri dish.
• Toxins: Harmful substances for living organisms
• Toxoid: Inactivated toxin used in vaccines
• Trophozoites: Active vegetative stage in the life cycle of some parasites
• Unicellular: Containing only one cell
• Vaccines: Immunizing substances to induce immunity to a specific microorganism
• Viable: Able to sustain life
• Virus: Small infectious agent that only replicates inside cells of another living organism.
• Vectors: Organism that transmit pathogens from host to host, frequently insects.
• Virulence: Degree of pathogenicity of a pathogen
• Vibrio: Comma-shaped bacteria
• Water: Important for bacterial growth.
• Weight loss: Decrease in weight.
• What are the sources of infection: Endogenous and exogenous infections.
• Whipworm: Infecting human through consuming contaminated food and water
• X-rays: Diagnostic test to view body structures and abnormalities.
• Yeasts: Unicellular organisms from the fungi kingdom.
• Zoonoses: Diseases transmitted between animals and humans.

Microbiology - Classification of Microorganisms

• Microorganisms are classified based on size, structure, and reproduction methods.
• Major groups include: bacteria, viruses, fungi, parasites, mycoplasma, and rickettsiae.
• Bacteria are classified by their shapes: cocci (spherical), bacilli (rod-shaped), and spirilla (spiral).
• Bacteria arrangements include:
  • monococcus (single)
  • diplococcus (in pairs)
  • staphylococci (grape-like clusters)
  • streptococci (in chains)
  • tetrad (in groups of 4)
  • sarcina (in groups of 8)
• Gram staining differentiates bacteria into gram-positive and gram-negative.
• Staining methods include gram stain, acid-fast stain, and simple stain.
• Bacteria can be identified through chemical testing.
• Examples of diseases caused by bacteria include boils, toxic-shock syndrome, osteomyelitis (severe bone infections)

Microbiology - Viruses

• Viruses are small infectious agents that only replicate inside cells of another living organism.
• Viruses are classified, based on; Human/animal virus, plant virus, insect virus, bacteria virus.
• Human viruses are categorized into; Respiratory viruses, Enteric viruses, Arboviruses.
• Types of viruses vary in diameter.
• Viruses are composed of nucleic acids (RNA or DNA but not both) and a protein coat, (called capsid).
• Different types of Viruses have different shapes, including polyhedral, spherical, helical, and complex.
• Viruses replicate through a lytic or lysogenic cycle.

Microbiology - Fungi

• Fungi are eukaryotic organisms that reproduce by spores.
• Yeasts, molds, and mushrooms are examples of fungi.
• Common applications of fungi include fermentation (e.g., of foods like beer, wine, and soy sauce) and in producing some antibiotics.
• Fungal infections in humans, also known as mycoses, can be superficial.
• Common examples of fungal infections include ringworm (tinea) and candidiasis.
• Fungi causes serious infection, such as, histoplasmosis and cryptococcosis.

Microbiology - Algae

• Algae are plant-like protists.
• Algae range from unicellular to multicellular forms.
• Algae have photosynthetic machinery.
• Four types of algae include; Brown algae, red algae, green algae, and blue-green algae (or cyanobacteria).
• Algae exposure can cause; Skin and eye irritations, allergic reactions, gastrointestinal upset.

Microbiology - Growth & Reproduction of Microorganisms

• Microorganisms, aim for growth and reproduction.
• Factors that regulate growth include nutrients (including carbon, nitrogen, phosphorus, sulfur, and vitamins/trace elements), moisture, temperature, gases (oxygen and air), pH (acidity and alkalinity), and osmotic pressure.
• Light and radiation also affect microbial growth.
• Microbial growth curves display four phases
  • Lag Phase, Exponential phase, Stationary phase and Death phase.
• Viral reproduction is accomplished through a lytic cycle or a lysogenic cycle.
• Fungal reproduction is through sporulation. Fungi commonly reproduce sexually or asexually.

Microbiology - Infection Control & Prevention

• Standard Precautions: Procedures used to reduce and prevent the spread of microorganisms.
• Standard Precautions should be applied to all patients.

Microbiology - Isolation Practices

• Isolation practices are used to prevent transmission of microorganisms from infected or colonized patients to other patients, visitors, and healthcare workers.
• It is divided into 3 types
  • Airborne precautions
  • Droplet precautions
  • Contact precautions

Microbiology - Handling & Disposal of Sharps

• Standard precautions must be used if there is a chance of body fluids being carried to another person through medical equipment.
• Use needles, syringes, and other items/instruments containing contaminants in puncture-resistant containers.
• Safely dispose of contaminated instruments/equipment.
• Safely manage needle stick injuries and splashes with body fluid.

Microbiology - Staff Health

• Prevention of acquiring infections via immunisation, covering lesions, restricting non-immune or pregnant staff.
• Prevention of transmitting infections by seeking medical advice when suffering infections, promptly reporting accidents and untoward incidents.

Parasitology - Introduction to Parasitology

• Medical parasitology is the study of parasites that infect humans.
• They cause diseases in many people in tropical countries, often resulting in severe medical conditions including blindness.

Parasitology - Definitions

• Parasitology: The study of parasites
• Parasite: An organism that benefits by living on or in another organism at the expense of the host.
• Parasitism: Symbiotic relationship where one party is benefited and one party is harmed.
• Obligate parasite: Parasites which is entirely dependant on the host
• Facultative parasite: Organism which can be parasitic but doesn't have to live as a parasite
• Ectoparasites: Parasites that live on the surface of the host.
• Endoparasites: Parasites that live within the body of the host.
• Commensal: A symbiotic relationship where one organism benefits and the other is neither benefited nor harmed.
• Host: An organism which harbors the parasite.
• Definitive host: The host that harbors the adult or sexually mature stages of a parasite.
• Intermediate host: The host that harbors the larval or asexual form of a parasite.
• Paratenic host: A host which act as a transporting agent for the parasite and in which parasites do not undergo any development.
• Compromised host: The host in whose normal defense mechanism has impaired, (e.g. AIDS).
• Pathogenicity: The ability of a parasite to produce a disease.
• Zoonosis: Diseases that can be transmitted between animals and humans.
• Virulence: Degree of pathogenicity of a pathogen.
• Vector: An agent (usually an insect), that transmit an infection from one host to another.

Parasitology – Common Protozoa

• Protozoa: Unicellular organisms
• Types of protozoa: Amoebae, flagellates, sporozoa, ciliates.
• Diseases of interest include; Entamoeba histolytica (amebiasis, trophozoites, precystic and cystic stages.), Trichomonas vaginalis. Malaria and Toxoplasma gondii.

Parasitology – Common Helminths

• Helminths: Large, multicellular organisms, (flatworms and roundworms.)
• Types of helminths include; fluke (trematodes), tapeworms (cestodes) and roundworms (Nematodes)
• Life cycle; Eggs, Larvae and Adults

Parasitology - Portal of Entry

• Portal of entry is the entry point for a parasite into the host.
  • Oral (mouth)
  • Skin
  • Sexual contact
  • Inhalation
  • latrogenic (medical procedure)

Parasitology - Diagnosis

• Fecal examination
• Serological tests
• Radiological examination
• Ultrasound
• Culture and sensitivity (stool/fluid)
• Sigmoidoscopy
• Mouth scraping/nasal discharge
• Tissue biopsy/skin

Parasitology - Treatment

• Drugs used in treating parasitic infections include; Metronidazole, Tinidazole, Paromomycin, Iodoquinol, and Albendazole, Mebendazole, Ivermectin.

Parasitology - Prevention

• Personal hygiene (handwashing)
• Cooking food thoroughly
• Proper water treatment/filtration
• Avoid contact with infected animals/vectors
• Proper waste disposal
• Wear appropriate protective clothing when in high risk areas

General Study Material

• Important information regarding treatment and prevention of certain diseases should be summarized across subjects.