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Microbiology: Infection, Disease, and Immunity Q&A, Exams of Advanced Education

Virginia Union University (VUU)Advanced Education

A concise overview of key concepts in microbiology, focusing on infection, disease, and the immune response. It covers topics such as bacterial examples, disease transmission, host defenses, and mechanisms of pathogen evasion. Questions and answers, making it useful for review and study. It also touches on the inflammatory response, phagocytosis, and adaptive immunity, offering a broad understanding of how the body interacts with pathogens. This material is designed to help students grasp the fundamentals of microbiology and immunology, preparing them for more advanced study. A valuable resource for students seeking to understand the complex interactions between pathogens and the host immune system.

Typology: Exams

2024/2025

Available from 06/05/2025

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BIOL 2230 Exam 3 Questions and
A Level Answers
What are pathology, etiology, and pathogenesis? - Pathology - the study of disease
Etiology - the cause of disease
Pathogenesis - studying the process of disease
How does the term disease differ from infection? - Disease - movement of the body
away from a state of "health"
Infection - colonization of the body by microorganisms
What are the three types of symbiosis? - 1) Mutualism (+/+) โ†’ Ex. E. Coli
2) Commensalism (+/0) โ†’ Ex. Candida albicans
3) Parasitism (+/-) โ†’ Ex. Vibrio cholera
What is normal flora? Examples? - Microorganism in/on the body at all times,
500 to 5,000 species at all times
Ex. Staphylococcus epidermidis, Lactobacillus acidophilus, E. Coli
What is microbial antagonism? Examples? - "Good bacteria," normal flora,
inhibit/prevent growth of pathogens
1) Out Compete: S. epidermidis
2) Change in Environment: L. acidophilus
3) Bacteriocins: inhibits bacterial growth, E. Coli
How is normal flora acquired? - L. acidophilus - vaginal birth
S. epidermidis - nursing
E. Coli - contaminated food, items
What are opportunistic pathogens? Examples? - Normal flora that can cause disease in
other locations of the body
Ex. E. Coli โ†’ UTI, wound, lungs, CSF
S. aureus โ†’ UTI, wound
What are probiotics? Examples? - Intentional ingestion of "good" bacteria to antagonize
"bad" bacteria
Ex. Yogurt, Fecal Transplant
What are Koch's postulates? - Method used to identify the etiological cause of an
infectious disease
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BIOL 2230 Exam 3 Questions and

A Level Answers

What are pathology, etiology, and pathogenesis? - Pathology - the study of disease Etiology - the cause of disease Pathogenesis - studying the process of disease How does the term disease differ from infection? - Disease - movement of the body away from a state of "health" Infection - colonization of the body by microorganisms What are the three types of symbiosis? - 1) Mutualism (+/+) โ†’ Ex. E. Coli

  1. Commensalism (+/0) โ†’ Ex. Candida albicans
  2. Parasitism (+/-) โ†’ Ex. Vibrio cholera What is normal flora? Examples? - Microorganism in/on the body at all times, 500 to 5,000 species at all times Ex. Staphylococcus epidermidis, Lactobacillus acidophilus, E. Coli What is microbial antagonism? Examples? - "Good bacteria," normal flora, inhibit/prevent growth of pathogens
  3. Out Compete: S. epidermidis
  4. Change in Environment: L. acidophilus
  5. Bacteriocins: inhibits bacterial growth, E. Coli How is normal flora acquired? - L. acidophilus - vaginal birth S. epidermidis - nursing E. Coli - contaminated food, items What are opportunistic pathogens? Examples? - Normal flora that can cause disease in other locations of the body Ex. E. Coli โ†’ UTI, wound, lungs, CSF S. aureus โ†’ UTI, wound What are probiotics? Examples? - Intentional ingestion of "good" bacteria to antagonize "bad" bacteria Ex. Yogurt, Fecal Transplant What are Koch's postulates? - Method used to identify the etiological cause of an infectious disease

What are some limitations to Koch's postulates? - 1) Some disease have multiple causes

  1. Some bacteria only cause disease in certain hosts
  2. Some microbes cannot be pure cultured
  3. Ethical concerns What are symptoms and signs? Examples? - Symptoms - a change in body function that is felt by a patient as a result of a disease Signs - a change due to a disease that a person can observe and measure What are meant by the terms communicable, contagious, and non-communicable? - Communicable - any disease that can be spread from one host to another Contagious - a disease that is easily spread from one person to another Non-Communicable - a disease that is not transmitted from one person to another How does incidence differ from prevalence? - Incidence - the fraction of the population that contracts a disease during a particular period of time Prevalence - the fraction of the population having a specific disease at a given time What is meant by the terms sporadic, endemic, epidemic, pandemic, and herd immunity? - Sporadic - a disease that occurs occasionally in a population Endemic - a disease that is constantly present in a certain population Epidemic - a disease acquired by many hosts in a given area in a short time Pandemic - an epidemic that occurs worldwide Herd Immunity - the presence of immunity in most of a population What are acute, chronic, and latent infections? - Acute - a disease in which symptoms develop rapidly but last for only a short time Chronic - an illness that develops slowly and is likely to continue or recur for long periods Latent - a condition in which a pathogen remains in the host for long periods without producing disease

Ex. Rabies What are the three routes of transmission? 1) - 1) Contact - a. Direct: handshake, intercourse, patient care b. Indirect: involves a nonliving object (fomite) c. Droplet: sneezing, coughing, talking, laughing

  1. Vehicle - airborne, waterborne, foodborne, "specimens"
  2. Vector - usually arthropods (biological and mechanical) What is a fomite? Examples? - Inanimate objects likely to transmit infection What are the primary portals of entry? - Broken skin and mucous membranes What are HAIs? (nosocomial infections) Significance? - Healthcare associated infections, infections acquired at a healthcare facility. 15% of patients get one, increasing, examples include MRSA and Pseudomonas aeruginosa Why are healthcare facilities susceptible? - Lots of reservoirs, invasive procedures, lots of compromised hosts What are common pathogens associated with HAIs? - Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa What precautions can be taken? - Handwashing, PPE, aseptic technique, isolation, education What is adherence? How might a host prevent it? - Pathogen must "bind" to host tissue. Fimbriae, M-Protein, Glycocalyx, Invasins What are biofilms? Examples? - A thin, slimy film of bacteria that adheres to a surface How do pathogens avoid the immune system? - 1) Capsules and M-Proteins
  3. Invasins
  4. IgA Proteases
  5. Coagulase
  6. Kinase

How do capsules and M-protein contribute to infection? - They inhibit phagocytosis What are invasins and IgA Protease? Examples? - Invasins - pathogens that invade a host cell to multiply and then lyse the cell IgA Protease - destroy the IgA antibodies that are abundant in mucous membranes How do coagulase and kinase enzymes contribute to infection? Examples? - Coagulase

  • clots blood, released by the pathogen, ex. Staphylococcus aureus Kinase - dissolves clots, released by the pathogen, ex. Streptococcus pyogenes What are four mechanisms of host damage? - 1) Direct Cell Lysis, ex. Salmonella
  1. Siderophores, ex. Yersinia pestis
  2. Collagenase & Hyaluronidase, ex. Clostridium perfringens
  3. Endotoxins & Exotoxins What are siderophores, collagenase, and hyaluronidase? - Siderophores - chemicals released by some bacteria that bind strongly to host nutrients Collagenase - enzyme that destroys connective tissues Hyaluronidase - enzyme that destroys connective tissues Who discovered bacterial exotoxins? - Emile Roux What are Type I, Type II, and Type III exotoxins? Examples of each? - Type I - super antigens, triggers an excessive (hypersensitivity) response (fever, vomiting, diarrhea, septic shock), ex. S. aureus Type II - hemolysis, breaks open RBCs, ex. S. pyogenes Type III - A/B toxins, either block protein synthesis or act as neurotoxins, ex. Clostridium botulinum What are endotoxins? Symptoms? Examples? - Ex. Lipopolysaccharides, most are harmless, some are toxic and cause excessive immune response What is septic shock? - An extreme and excessive immune response, extremely low blood pressure, fever, vomiting What are common exit portals? - Usually the same as portals of entry, Ex. Respiratory and urinary tract

Macrophages - eat the bacteria and constantly release waste to be able to continue eating How is phagocytosis performed? - How do some pathogens avoid phagocytosis? - Capsules and m-proteins What is the complement system? - A collection of blood proteins that can be activated in a cascade of reactions, activation can be triggered non-specifically through antibodies and manose (LPS), complement defends by oponization, trigger inflammation, and membrane attack complex What are three outcomes of the complement cascade? - 1) Oponization

  1. Trigger Inflammation
  2. Membrane attack complx How does each contribute to immunity? - Oponization - it puts active complement proteins on the pathogen for the macrophage to consume Trigger Inflammation - Membrane Attack Complex - places active complements in a circle on the pathogen and causes cell lysis Why are endotoxin (LPS) and mannose important? - They are the triggers for the complement system, manose is non-specific and antibodies are specific How do cytokines contribute to immunity? - Cytokines are hormone-like substances that influence the behavior of cells involved with the immune system. Example: Interleukin - some act as pyrogens and trigger fevers What are interferon and interleukin? - Interferon - non-specific defenses against viruses Interleukin - some act as pryogens and trigger fevers How are fevers generated? Purpose? - How does interferon function? - 1) Virus infects host cell
  3. Infected host cell secretes interferon
  4. Interferon binds to receptors on neighboring cell to produce Anti-Viral Proteins (AVPs)
  1. AVPs destroy all mRNA which prevents viral replication Who discovered antibody-mediated immunity? - Emil von Behring What is adaptive (specific) immunity? - What are antibodies? Structure? - Large glycoproteins, immunoglobulins, 4 polypeptide chains, 2 heavy chains and 2 light chains with two antigen binding sites What are antigens, haptens, and immunogens? - Antigens - a substance (foreign) that binds to antibodies and may illicit and immune response Haptens - illicit an immune response when bound with something else Immunogens - illicit an immune response How do antibodies contribute to immunity? - 1) Opsonization
  2. Aggluination
  3. Neutralized
  4. Complement Activation
  5. Trigger Inflammation What roles do IgG, IgM, IgA, IgD, and IgE play in the immune response? - IgG - most abundant in serum (80%), monomers, defends by all mechanisms except triggering inflammation, cross placents IgM - first antibodies produced following antigen, secreted from B-cells as pentomeres, monomers are placed on the surface and serve as B-cell receptors IgA - abundant in mucous, saliva, and breastmilk, secreted from B-cells as dimers IgD - literally no one knows IgE - located on surface of mast cells and trigger inflammation, involved with hypersensitivity and allergies Which are monomers, pentamers, and dimers? - Monomers - Pentamers - Dimers -

What is Major Histocompatibility Complex (MHC)? - The genes that code for histocompatibility antigens; also known as leukocyte antigen (HLA) complex What roles are played by MHC-2 and CD4 proteins? - MHC- 2 - the host cell uses this to display things on the surface of the cell CD4 - a protein on the t-cell that binds to MHC- 2 What roles are played by cytokines, such as interleukin? - A small protein released form human cells that regulate the immune response; directly or indirectly may induce fever, pain, or t-cell proliferation. What are dendritic cells? - A type of antigen-presenting cell characterized by long finger like extensions; found in lymphatic tissue and skin What is the cell-mediated immune response? - 1) Infected/damaged host cell displays antigen on its surface using MHC-1 protein

  1. Appropriate cytotoxic t-cell binds to displayed antigen using t-cell receptor and Cd protein
  2. Cytotoxic t-cell secretes perforin and granzyme
  3. Perorin forms a pore in host cell through witch granzme enters and triggers pre- programmed cell death What are Cytotoxic T-Cells? Function? - What roles are played by MHC-1 and CD8 proteins? - What are perforin, granzyme, and apoptosis? - Perforin - protein that makes a pore in a target cell membrane, released by cytotoxic T-lymphocytes Granzyme - proteases that induce apoptosis Apoptosis - the natural programmed death of a cell; the residual fragments are disposed by phagosytosis How do the roles of MHC-1 and MHC-2 differ with regards to an immune response? Importance? - Immune cells will always use MHC-2, CD8 binds to MHC-1, CD4 binds to MHC- 2 What are Natural Killer Cells? - Destroy cells that do not have MHC proteins Ex. Parasites, amoebas, worms, giardia

What are autoimmune diseases? Examples? - Result when b-cell receptors recognize self-molecules What are vaccines? - Artificial exposure to antigen in order to develop an active immune response How were vaccines discovered? - Edward Jenner tried variolation using cow pox scabs to protect against small pox What are the various types of vaccines? Effectiveness? - Attenuated Whole Agent - the whole virus, weakened, but "live," ex. MMR Inactivated Whole Agent - "dead" virus, ex. Influenza Subunit - (pure, single antigen [not altered at all]), ex. Hepatitis B Vaccine - single antigen, ex. Hepatitis B Toxoid - ex. Tetanus and diptheria