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Microbiology Final Exam

Terms in this set (168)

What is epidemiology?
Science that evaluates occurrence, determinants, distribution, and control of health and disease in a defined human population
Morbidity rate (new cases)
(# of new cases in time interval / total population size) x 100
Prevalence rate (total number of cases)
(# of cases in population / total population) x 100
Mortality rate (deaths)
(# of deaths due to given disease / total population size with disease) x 100
What is incidence?
Number of people who develop a disease during a particular time period
What is prevalence?
Number of people who develop a disease at a specified time, regardless of when it first appeared
What is a sporadic disease?
Disease that occurs only occassionally
What is an endemic disease?
A disease constantly present in a population
What is an epidemic disease?
Disease unexpectedly acquired by many people in a given area in a short time
What is a pandemic disease?
A worldwide epidemic
What is acute disease?
Symptoms develop rapidly but disease lasts only a short time (ex: influenza)
What is a chronic disease?
Symptoms develop slowly (ex: tuberculosis)
What is a subacute disease?
Intermediate between acute and chronic
What is a latent disease?
Causative agent is inactive for a time but then activates and produces symptoms (ex: herpes virus)
What is herd immunity?
Immunity in most of the population
What is a local infection?
Pathogens are limited to a small area of the body (ex: respiratory infection)
What is a systemic (generalized) infection?
An infection throughout the body (ex: measles)
What is a focal infection?
Systemic infection that began as a local infection
What is sepsis?
Toxic inflammatory condition from the spread of microbes, especially bacteria or their toxins, from a focus of infection
What is subclinical disease?
No noticeable signs or symptoms (healthy, resistant host)
What is a primary infection?
Acute infection that causes the initial illness (healthy, but susceptible host)
What is a secondary infection?
An opportunistic infection after a primary infection (compromised & susceptible host)
What is common source spread?
A noncommunicable disease that results from a single common contaminated source (ex: food poisoning)
What is propagated spread?
A communicable disease that results from the introduction of a single infected individual into a susceptible population which is propagated to others
What are the three types of common source epidemics?
1) Point source spread - common source occurs for a short time period (ex: bad food)
2) Continuous common source spread - infection occurs for an extended period of time (ex: bad water)
3) Intermittent common source spread - infection occurs for a period, stops, and then begins again (ex: water contaminated during flooding)
What are three reservoirs for infection?
Human, animal, nonliving
What is direct contact transmission?
Requires close association between the infected and a susceptible host
What is indirect contact transmission?
Spread to a host by a nonliving object (fomite)
What is droplet transmission?
Transmission via airborne droplets (less than one meter)
Mechanical transmission vs. biological transmission
Both are vector transmission
- Mechanical: arthropod carries pathogen on its feet
- Biological transmission: Pathogen reproduces in vector, transmitted via bites or feces
Pseudomonas is a prevalent ___________ or HAI.
nosocomial
What are PAMPs?
Pathogen-associated molecular patterns that are associated with groups of pathogens and recognized by cells of the innate immune system.
What is innate immunity?
A nonspecific response present before exposure to infectious agent. Includes inflammatory response and fever.
What is adaptive immunity?
A response that develops after exposure to an agent & that has memory. Includes humoral response that produces antibodies that binds to targets. Also includes cell-mediated response that directly destroys targets.
How does the lymphatic system aid the immune system?
- Contains lymphocytes and phagocytes
- Lymph carries microbes to lymph nodes where lymphocytes and macrophages destroy the pathogen.
What is the role of mucus in the immune system?
Viscous glycoproteins trap microbes and prevent tracts from drying out
What does the lacrimal apparatus do?
Drains tears and washes eye
What does the mucociliary escalator do?
Transports microbes trapped in mucus out of the lungs
What is commensalism?
One organism benefits while the host is unharmed
What are probiotics?
Live microbial cultures administered to exert a beneficial exert
What does sebum do?
Forms a protective film and lowers pH (3-5) of skin
What do lysozymes do?
Destroy bacterial cell walls in perspiration, tears, saliva, and urine.
What are AMPs?
Antimicrobial peptides - short peptides produced in response to protein and sugar molecules on microbes.
Where are acute phase proteins produced?
Liver
What are siderophore proteins?
Proteins produced by bacteria to compete with host iron-binding proteins to scavenge iron
What are the major players in all 3 complement pathways?
C3a (inflammation) and C3b (cytolysis and opsonization)
What is cytolysis?
Activated complement proteins create a membrane attack complex (MAC)
What is opsonization?
Promotes attachment of a phagocytes to a microbe
What is inflammation?
Activated complement proteins bind to mast cells, releasing histamine
What are interleukins?
Cytokines that control every aspect of immunity
What are chemokines?
Cytokines that propagate chemotactic signals for each immune cell type
What are interferons?
Cytokines for viral immunity.
- Type I: Produced by infected cells, causing neighboring host cells to produce viral replication inhibiting proteins
- Type II: Causes neutrophils and macrophages to kill bacteria
What measures leukocytes in the blood?
White blood cell counts
Erythrocytes (red blood cells), leukocytes (white blood cells), and thrombocytes (platelets) are created in red bone marrow via what process?
Hematopoiesis
What are granulocytes?
Leukocytes with granules in their cytoplasm that are visible with a light microscope. Includes neutrophils, basophils & mast cells, and eosinophils
What are neutrophils?
Granulocytes that are phagocytic. Work in early stages of infection.
What are basophils and mast cells?
Granulocytes that release histamine and work in allergic reactions
What are eosinophils?
Granulocytes that are phagocytic and produce toxic proteins against parasites and helminths
What are agranulocytes?
Leukocytes with granules in their cytoplasm that are not visible with a light microscope. Includes monocytes and dendritic cells.
What are monocytes?
Agranulocytes (leukocytes) that mature into macrophages in tissues that are phagocytic
What are dendritic cells?
Agranulocytes (leukocytes) that are found in the skin, mucous membranes, and thymus; phagocytic
What are lymphocytes?
Agranulocytes (leukocytes) that consist of natural killer cells, T cells, and B cells.
The three kinds of lymphocytes are natural killer cells, T-cells, and B-cells. What are each of their functions?
- NK cells produce perforin & granzymes to kill infected & cancerous cells
- T cells are part of cell-mediated immunity
- B cells produce antibodies
What is margination?
Sticking of phagocytes to blood vessels in response to cytokines at the site of inflammation
Phagocytes squeeze between endothelial cells of blood vessels via _______________
diapedesis
What are the Greek roots behind "phagocyte"
Phago- means eat and -cyte means cell
________________ macrophages are residents in tissues and organs
Fixed
______________ macrophages roam tissues and gather at sites of infection
Free (wandering)
What are the four stages of phagocytosis?
1) Chemotaxis: Chemical signals attract phagocytes to microorganisms
2) Adherence: Attachment of a phagocyte (TLR) to the surface of the microorganism (PAMP)
3) Ingestion: Opsonization
4) Digestion: Microorganism digested in phagolysosome
What is opsonization?
Microorganism is coated with serum proteins, making ingestion easier
What are TLRs?
Toll-like repectors on phagocytes that attach to PAMPs that are associated with pathogens and recognized by phagocytes.
TLRs bound to PAMPs induce
the release of ___________
from innate immune cells
that regulate the intensity
and duration of immune
responses
cytokines
What are the 5 signs and symptoms of inflammation?
1. Erythema (redness)
2. Edema (swelling)
3. Heat
4. Pain
5. Altered function
How does a fever work in immune function?
Slows mesophilic bacterial growth. Caused when hypothalamus (normally at 37 degrees C) releases prostaglandins in response to cytokines. Body constricts blood vessels, causing shivering (to raise temp)
_______________ immunity uses various systems to help phagocytes do phagocytosis.
Adaptive
What are the two subsections of adaptive immunity?
1. Humoral immunity - antibodies, b cells
2. Cell-mediated immunity - antigen presentation, T cells
What are cytokines?
Chemical messengers of immune cells.
What are antigens?
Immune response triggers, made up of fragments called epitopes.
Humor immunity fights antigens ______ of the host cell. Cell-mediated immunity fights antigens _____ of the host cell.
outside, inside
How does humoral immunity fight infection?
Produces plasma cells to secrete protein antibodies to combat antigen. B cells are lymphocytes that recognize antigen and make antibodies.
How does cell-mediated immunity fight infection?
Produces cytotoxic T lymphocytes to destroy infected cells
Tumor necrosis factors (TNF) are a type of cytokine. What do they do?
Involved in inflammation of autoimmune disease
What do hematopoietic cytokines do?
Control stem cells that develop into red & white blood cells
What are the events in humoral immunity?
Antibodies, antigen-antibody binding, MHC & antigen presentation, clonal selection & expansion of B cells.
What are antibodies?
Secreted proteins also called immunoglobulins (Ig). Valence refers to the number of antigen-binding sites on an antibody.
IgM structure and function
- 10 binding sites
- Causes clumping of cells and viruses
- First response to an infection, but short lived
IgG structure and function
- Monomer (very small)
- 80% of serum antibodies
- Cross the placenta
IgA structure and function
- Monomer in serum; dimer in secretions
- Prevent microbial attachment to mucous membranes
IgE structure and function
- Monomer
- Cause the release of histamines when bound to antigen
- Lysis of parasitic worms
IgD function
Unknown, assists in immune response on B cells in some way
What is the role of the antigen-antibody complex in humoral immunity?
Protects the host by tagging cells/molecules for destruction by phagocytes and other cells
What is agglutination?
Clumping bacteria together to reduce number of infectious units to deal with
What is neutralization in terms of humoral immunity?
Blocking adhesion of bacteria and viruses or blocking attachment of a toxin.
What is antibody-dependent cell-mediated cytotoxicity (ADCC)?
Antibodies cause destruction by macrophages, eosinophils, and NK cells
What is activation of complement in terms of humoral immunity?
Complement binds to antigen-antibody complex at the antibody end, causing inflammation and cell lysis.
What do Class I MHC cells do?
They are on the surface of all nucleated cells and identify "self" from "nonself"
What do Class II MHC cells do?
They are on the surface of antigen-presenting cells (APC) and identify phagocytes that are fighting an infection.
What does MHC stand for?
Major histocompatibility complex, which are proteins on the surface of host cells.
What are APCs?
Antigen-Presenting Cells
B cells are a key component of humoral immunity. How do they function?
Combat extracellular pathogens.
- mature in bone marrow
- Migrate to lymphatic system
- Attach to antigens via B-cell receptors (BCRs). This is the first step in activating T-independent immunity
What two ways can B cells be activated?
1. Direct activation by rogue T-independent antigen
2. Activation by T-dependent antigen through MHC II and T helper cells
Does T-independent antigen produce memory cells?
Does T-dependent antigen produce memory cells?
No
Yes
True or false: B cells can act as antigen-presenting cells (APCs) to bind to protein antigens
True
What does colonial expansion do in t-independent antigen response?
Differentiates B cells into:
- Anti-body producing plasma cells for primary response
- Memory cells for secondary immune response
- Clonal deletion eliminated harmful B cells
True or false: During clonal selection & expansion, only B cells or T cells specific for the current antigen are activated.
True
What are the components of cell-mediated immunity?
- Antigen presenting cells (APC)
- T-helper cells (Th cells)
- Extracellular killing
- Clonal selection & expansion of T cells
What does colonial expansion do in t-dependent antigen response?
Differentiates T cells into:
- Active Th and Tc cells for primary response
- Long-lived memory Th cells for secondary response
- Clonal deletion eliminates harmful T cells (self-reacting)
What do cytotoxic T lymphocytes (CTL or Tc cells) do?
Kill self cells altered by infection/cancer... done by carrying non-self antigens + MHC class I on the surface
What are perforin proteins?
Proteins that cause pores to form in the plasma membrane like the complement MAC
What do granzyme proteins do?
Induce apoptosis
What is apoptosis?
Programmed cell death for damaged or infected cells. Phagocytes clean everything up
True or false: Natural killer cells kill with MHC class I in cells infected with viruses, microbes, or tumor cells.
False
Antibody-dependent cell-mediated cytotoxicity (ADCC)
1. Targets coated with antibodies
2. Immune system cells attach to Fc regions of antibodies
3. Target cell lysed by immune system chemicals
True or false: Only t-dependent humoral and cell-mediated responses generate memory cells
True
True or false: T-Independent antigen responses generate memory cells
False
_________________ is the relative amount of antibody in serum and reflects the intensity of the humoral response
Antibody titer
Of the following four examples of acquired immunity, which produce memory?
- Infection
- Maternal antibodies
- Vaccination
- Immune globulin therapy
Only infection and vaccination would result in memory
What is variolation?
Inoculation of small pox into the skin
What are live attenuated vaccines?
Weakened strains of pathogen that closely mimic an actual infection and provide lifelong cellular & humoral antibody immunity. Ex: chicken pox, measles
What are inactivated killed vaccines?
Killed/chemically inactivated pathogen, require repeated boosters, induce mostly humoral immunity. Ex: Rabies, influenza
What are subunit vaccines?
Use antigenic fragments to stimulate immune response. Some are recombinant (closed pathogen gene in harmless host). Ex: Whooping cough, meningitis
What are toxoid vaccines?
Inactivated toxins produce immune response. Alternative to older antitoxins. Ex: Tetanus, botulism
What are conjugated vaccines?
Used for children with poor immune responses. Conjugate a protein toxoid to polysaccharide for T-dependent immune response. Ex: Haemophilus influenzae B
What are DNA/RNA vaccines?
Cause host cell to produce microbe protein antigen to stimulate T-dependent immune response. Ex: EUA for mRNA COVID vaccine
What are two factors to a diagnostic immunology test?
Test sensitivity (low false negative %) and test specificity (low false positive %).
Antibody structure
A Y shaped molecule with most being constant and just the tips (antigen binding sites) being the variable regions. Made of 4 separate polypeptide chains joined by dilsulfide bridges.
What is a hybridoma?
An "immortal" cancerous B that produces monoclonal antibodies, which are highly specific to one antigen
Precipitin ring test
a cloudy line forms where there is the optimal ratio of antigen and antibody
Immunodiffusion test
A test consisting of precipitation reactions carried out in an agar gel medium
Direct agglutination assay
Any test that uses whole cells as a direct means of looking for antibodies binding to antigens
Florescent-Antibody Test
Direct ELISA
Directly detects antigen with enzyme-linked antibodies
Indirect ELISA
Indirectly detects antigens by interacting with serum antibodies
What does ELISA stand for?
Enzyme-linked immunosorbent assay
What is soil microbiology?
Scientific stud of organisms (including microbes) in soil, their functions, and how they affect soil properties.
What is an example of symbiosis between animals and microbes?
Skin and intestinal flora
What are examples of symbiosis between plants and microbes?
- Rhizobium spp. are nitrogen fixing bacteria
- Mycorrhizae are a fungi that extend root surface area (0.25" of plant root can have up to 9 ft of fungi associated with it)
____________ are chemicals that do not naturally occur in nature that are resistant to degradation by microbes.
Xenobiotics
What is bioremediation?
The use of living organisms, such as prokaryotes, fungi, or plants, to detoxify a polluted area
What is bioaugmentation?
Addition of specific microbes to degrade a pollutant
What are the three subsections of aquatic microbiology?
- Marine microbiology
- Water treatment
- Wastewater treatment
What are the different aquatic zones?
Chemoautotrophs oxidize _____ to make sugar in the absence of light.
H2S
What is eutrophication?
excessive richness of nutrients in a lake or other body of water, frequently due to runoff from the land, which causes a dense growth of plant life (algal & cyanobacterial blooms) and death of animal life from lack of oxygen.
What is the primary indicator organism for water purity tests?
E. coli, a coliform
The presence of coliforms is determined by...
Most probable number
Membrane filtration method
Colilert test
Membrane filtration technique
Colilert test
Describe the processes that wastewater undergoes in a treatment plant.
- Primary sewage treatment to remove solids
- Secondary sewage treatment by aerobic microbial oxidation
- Disinfection by chlorine to kill enterics & release of water
- Sludge digestion of solids by anaerobic bacterial oxidation
- (OPTIONAL) Tertiary sewage treatment of water for drinking
What is biological oxygen demand (BOD)?
A measure of the amount of dissolved oxygen microorganisms use up as they decompose organic wastes found in water
What are the pros and cons of centralized sewage treatment plants?
Pros: allow for high population density and complete treatment
Cons: Very expensive to build and maintain
What are pros and cons of decentralized septic tanks & oxidation ponds?
Pro: Very inexpensive to build and maintain
Cons: Takes longer to treat sewage and always release secondary effluent, possible containing pathogens, into the environment
What does HACCP stand for? What is it?
Hazard Analysis and Critical Control Point. Mandatory for FDA and USDA regulation to preventative food safety.
What was FSMA?
Food Safety Modernization Act (2011). New mandatory HARCP plan.
What are the two primary types of food-borne disease?
1. Food-borne diseases
2. Food intoxication
What is commercial sterilization?
Steam under pressure in a retort (basically a food autoclave). Kills spoilage microbes, but not necessarily all microbes in food.
What is 12D treatment?
Quality control test to ensure commercial sterilization... must hill endospore-forming Clostridium botulinum
Pasteurization
Kills pathogens and substantially reduces number of spoilage organisms
What are the three kinds of canned food spoilage?
- Thermophilic anaerobic spoilage
- Flat sour spoilage
- Mesophilic bacteria spoilage
What is pascalization?
High pressure used in food industry to kill microbes. Does NOT destroy endospores.
What are GRAS chemical agents?
Generally Recognized As Safe
What are bacteriocins?
Bacterial defense proteins. May be sprayed into ready-to-eat lunch meat bags to kill Listeria monocytogenes.
True or false: Low temperatures kill microbes, preventing growth.
False, it only SLOWS microbial growth.
Yeast for beer production produces ethanol by ____________________.
anaerobic fermentation
What are biosurfactants?
Surfactants with both hydrophobic & hydrophilic regions that are used to emulsify, increase detergency, dispersion, and solubility of oils
What are bioconversions?
Minor changes in molecules carried out by non-growing microbes.
What are biosensors?
Living microbes, enzymes, or organelles are linked to electrodes to detect specific substances.
Biofuels can produce as much as _______ the energy/acre than corn.
40x
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