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208 Cards in this Set
- Front
- Back
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What do almost all prokaryotes have that eukaryotes do not? What do eukaryotes have instead? What do prokaryotes not have that eukaryotes do?
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Cell wall
Cell membrane Organelles |
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What are the two main functions of the cytoplasmic membrane in bacteria?
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Regulates passage of nutrients, waste products and secretions in and out of cell.
Energy transfer (ATP production) - functions like mitochondria. |
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What are the four components of a gram-negative cell envelope from outside in?
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Outer membrane, cell wall, periplasmic space, cytoplasmic membrane
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What are the three components of a gram positive cell envelope from the outside in?
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Cell wall, sometimes periplasmic space, cytoplasmic membrane
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What makes up the gram positive cell wall?
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Cross-linked peptidoglycan layer (aka murein)
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What does the gram positive cell wall contain that provides a negative charge?
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Teichoic acids - linkages w/ lipids in cytoplasmic membrane - extend from cell wall
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What allows gram positive bacteria to withstand hydrophobic compounds like bile salts in the intestines?
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Cell wall
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What form the exterior layer of mycobacteria? Are they hydrophilic or hydrophobic?
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Mycolic acids
Hydrophobic |
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What are 4 notable clinical implications of bacterial cell walls?
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Ligands for adherence and receptor sites for drugs/viruses.
Can cause symptoms of disease. Immunological distinction and immunological variation among bacteria strains. Can be cleaved by lysozymes. |
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How are antibiotics able to inhibit activity at the cell wall causing autolysis or preventing growth? What are two examples of antibiotics with this action?
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Through murein synthesis inhibition.
Penicillin, cephalosporins |
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What are 3 notable characteristics of the gram negative outer membrane of lipopolysaccharide?
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Lipid nature excludes hydrophilic compounds - porins needed for nutrient passage.
Protects against lysozymes. Blocks some abx. |
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What are the 3 components of the lipopolysaccharide of gram negs?
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Lipid A, Core, O Antigen
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What do low levels of Lipid A cause in gram neg infections?
What do high levels of Lipid A cause? |
Low levels: fever and mobilization of host defenses.
High levels: endotoxin causing shock and death. |
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What is a major characteristic of O antigen in the lipopolysaccharide of gram negs?
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Highly variable - distinguishes diff gram neg species
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What is contained in the periplasmic space?
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Enzymes - beta lactamase which allows resistance to certain abx
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What is a disadvantage for the bacteria caused by the double membrane in gram negs?
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Allows for attachment of bacteriophages
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What is an example of an abx that interferes w/ cell membrane function causing cell death?
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Amphotericin B
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What is a bacteria that does not have a cell wall? How does it stain?
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Mycoplasma. Weakly gram +
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What two things are flagella used for to classify bacteria?
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Number and arrangement, antigenic properties
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What are 2 functions of pili (fimbriae)?
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Initial attachment to specific host cell receptor, attachment for transfer of DNA btwn bacteria (much longer sex pili)
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Capsule
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Slimy.
Difficult to phagocytize. Sero typing. Vaccines. Stimulate ab formation. |
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What allow spores virulence?
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Resistance to heat, cold, drying and most chemicals.
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What are the two steps at which many abs work on ribosome subunits to effect protein synthesis? What is an example abx that functions this way?
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Steps: Initiation or elongation.
Ex: Rifamin |
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How many chromosomes do bacteria have?
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One double strand DNA
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What is an example abx that effects DNA replication?
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Metronidazole
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What are 4 important functions that plasmids carry genes for?
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Resistance, code for exotoxin production, production of bacteriorcins, formation of pili
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What is a disease?
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Symptomatic infection
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What are primary pathogens?
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Microbes that can cause disease in immunocompetent.
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What are two examples of opportunistic pathogens?
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Pneumocystis jirovecci, Pseudomonas aeruginosa
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What is the definition of virulence?
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The degree of an organism's pathogenicity measured (relative measure) by the # of organisms required to cause damage to host (infection)
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What are the symptoms of foodborn illness of E. coli 0157?
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Cramps, fever, bloody diarrhea, kidney failure (HUS), possible death
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What is the equation that demonstrates the relationships involved in infection?
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Infection = dose of microbes x virulence/ host resistance
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Why is Chlamydia an obligate intracellular pathogen?
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Need cells' metabolic pathways including ATP
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What is Rickettsia an obligate intracellular pathogen?
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Its membrane is leaky
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What is an obligate intracellular pathogen that lives w/in PMNs?
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Erlichia
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What are the two processes involved in adhesion? What 3 strategies are used in this process?
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Receptors (integrin) on the host cell, adhesins (ligands) on the bacterial cell.
Strategies: Pili, Capsule, Surface proteins |
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How do pili (fimbrae) allow for adhesion?
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Attach to epithelium via tip proteins. The specific shape corresponds to host receptors. Resistant to flushing.
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What are 3 examples of organisms with glycocalyx?
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S. epidermidis, Pneumococci (vaccine available) and meningococci (vaccine available)
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What is hemagllutinin?
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Adhesin. Key in viral attachment - surface proteins on virus. Host cell cell surfaces have sialic acid which allows for attachment of hemagglutinin.
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What is the function of exopolysaccharides?
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Attachment and biofilm production.
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What is a surface protein that interferes with phagocytosis?
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M protein - Strep pyo
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What is an example of an organism that prevents ingestion by phagocytosis? How does it do this?
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M. TB. Waxy cell wall resists phagocytosis.
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What is an example of an organism that survives after phagocytosis by inhibiting lysosome fusion with phagosome?
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Toxoplasma
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What are two examples of organisms that survives after phagocytosis by escaping into the cytoplasm of the host cell?
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Shigella, Listeria
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What is an example of an organism that survives after phagocytosis by destroying the phagosome membrane?
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Rickettsia
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What is an example of an organism that survives after phagocytosis by inhibiting the oxidative burst?
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Legionella
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What is an example of an organism that survives after phagocytosis by resisting lysosomal enzymes (innate)?
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Leishmania
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What are two ways that organisms are able to interfere with complement?
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1) Cover their capsule components that might activate complement.
2) Incorporate sialic acid into surface which takes on host cell appearance and directly inhibits complement. |
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What do leukocidins (exotoxin) do and what is an example of an organism that produces this?
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Destroys WBCs by lysis.
S. aureus |
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What does IgA protease do and what is an example of an organism that produces this?
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Degrades IgA.
N. gonorrhoaea |
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What does kinase do?
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Overcomes body's attempt to coat w/ fibirn to prevent further tissue spread.
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What does Hyaluronidase do?
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Breaks down hyaluronic acid ("cement") that holds cells together
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What does Lecithinase do?
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Breaks down lecithin phospholipids in cell membranes
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What does alpha hemolytic hemolysin do?
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Converts hemoglobin to methemaglobin
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What does urease do? What are two organisms that produce this?
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Hydrolyzes urea in a harsh environment to ammonia in which it can survive.
H. pylori, Proteus spp |
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What does collagenase do and what is an organism that produces this?
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Enzyme that breaks peptide bonds in collagen to facilitate spread.
Clostridium. |
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What constitutes neutropenia?
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Absolute <1500
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What CD4 contstitutes AIDS?
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Below 200
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What are two adverse results of a splenectomy?
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Decreases IgM/humoral immunity, increases risk of severe infection by encapsulated organisms: S. pneumo, N. meningitidis, H. influenzae
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What are the 3 vaccines one should get w/ a splenectomy?
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Polyvalent pneumococcal vaccine, quadravalent meningococcal polysaccharide, haemophilus b conjgate
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How do corticosteroids decrease humoral immunity?
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Causes hypogammaglobulinemia
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What is an adverse effect of corticosteroids?
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Increased risk of invasive infections by encapsulated, pyogenic bacteria
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What type of antibodies do babies get while breastfeeding?
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IgA
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What is a convalescent period?
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Time during which patient recovers from illness. May still be contagious.
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What are bacteriophages?
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Viruses that infect bacteria
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Is vertical transmission (transplacental) direct or indirect transmission?
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Direct
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What are three forms of indirect transmission?
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Vehicle borne (phone, door knob), Vector born (mosquito), Air borne (coughing, sneezing)
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What is the central activity of the non-specific inflammatory response?
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Phagocytosis
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What do monocyte/macrophages do besides degrading larger bacteria in phagocytosis?
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They can produce interferons which inhibit viral replication
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What are the 4 main events in an inflammatory response?
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Dilute potentially toxic agents by increasing blood flow, enhance phagocytosis, release inflammatory mediators, trigger complement cascade
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What is the mechanism in phagocytosis that actually kills the organism?
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Oxidative burst
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What is the function of histamines in chemotaxis in an immune response?
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Increase capillary permeability
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What inflammatory mediators produce fever?
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Interleukins, TNF
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How many days is the lag period until sufficient IgM is produced in a primary response?
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7-10
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During a secondary response, how many days lag period until IgG is at hightened response?
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3-5 days
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What is the half life of IgM?
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5 days
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What are CD4 and CD8 cells?
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CD4: T helper cells
CD8: Cytotoxic T cells |
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What activates CD4 T helper cells? What are CD4 cells role? And what do they release?
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Activated by ag binding. They differentiate B cells and CD8 cells. They release macrophage activators (cytokines)
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What do CD8 cytotoxic T cells do?
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Once activated, recognize foreign cells or virus infected cells.
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What feature of prokaryotes is the basis of the selective action of penicillin?
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Cell wall
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How does the protective outer membrane present in bacteria w/ thin cell walls contribute to symptoms seen?
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LPS in gram negatives
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What structures allow bacteria to overcome the repelling action seen from electro charges?
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Pili - long pili can reach far enough to avoid repellent
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What impact on disease and health results from the coating of bacteria by organized clycocalyx?
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Capsule - allows for vaccines to be made, encapsulated organisms more virulent
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What steps must occur for human contact w/ microbes to result in disease?
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Attachment
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What is an example of an intermediate host?
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In Lyme disease, humans are the intermediate host
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How would you indirectly identify antibody?
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Determine antibody activity via reaction: agglutination or complement fixation
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How would you directly identify antibody?
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Measure the specific antibody via: enzyme linked, indirect fluorescent ab, western blot
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What are two types of antigen detection tests?
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Ab-coated latex beads, radioimmunoassay
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What is sensitivity?
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Likelihood a test will be positive if the pathogen is present
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What is specificity?
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Likelihood a test is negative if the pathogen is absent
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By what era were antibiotics freely used: physician prescribed, over the counter and consumer demand?
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Mid-1900s
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What is an antibiotic?
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Low molecular weight, interferes w/ spec activities of certain types of organisms, natural substances that inhibit growth or proliferation of bacteria or kill them directly
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What are 3 things that might contribute to your "best guess" of what a pathogen might be when determining antibiotic use?
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Infection site, community acquired?, host age and predispositions
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What are 4 host factors to think about when determining antibiotic use?
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Past adverse reactions, renal/hepatic function, other meds, age/pregnancy
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What are 5 drug factors to think about when determining antibiotic use?
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Activity against pathogen, ability to reach infection site, available routes of admin, dosing freq, cost
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What is a common adverse affect of Erythromycin?
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Significant GI upset
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What is a common adverse affect of Tetracycline?
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Can effect growing teeth
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What is the best tolerated antibiotic of all abx?
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Flouoquinolones
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What is a drug/food interaction of Erythromycin?
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Reduces activity of H1 antagonists
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What is a drug/food interaction of Flouroquinolones?
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Increases serum levels of theophylline
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What is a drug/food interaction of Tetracycline?
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Absorbtion is decreased when combined w/ milk, antacids, and calcium supplements
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What is a drug/food interaction of Flagyl?
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Structure is similar to antabuse which makes one violently ill when drinking alcohol
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What are 4 characteristics of the ideal antibiotic?
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Destroys pathogens, non-toxic to host, chemically stable, able to reach site of infection in host
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What are 6 examples of bactericidal abx?
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Pens, cephalosporins, aminoglycosides, vanco, quinolones, polymyxins
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What are 3 examples of bacteriostatic abx?
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Macrolides, sulfonamides, chloramphenicol
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What is an example of a combo therapy that is synergistic?
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Augmentin (amoxicillin and clavulanic acid)
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What are the 5 main mechanisms of abx action?
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Bacterial wall synth, bacterial protein synth, bacterial DNA synth, bacterial RNA synth, Anti-folates
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What are the 4 main classes of beta-lactams?
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Penicillins, Cephalosporins, Carbapenems, Monobactams
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What are the differences in the generations of Cephalosporins?
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1st: Gram +, 2nd: also H. influenza, 3rd: also good CSF levels
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What are the 4 types of penicillins?
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Penicillins, anti-staphylococcal penicillin, aminopenicillins, anti-pseudomonal penicillin
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What are the two broad types of antibiotics that affect bacterial wall synthesis?
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Beta-lactams, glycopeptides
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What is a major type of glycopeptide abx?
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Vanco
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What can you do to overcome the resistance factor: beta-lactamase, with abx that affect bacterial wall synthesis?
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Combine with other meds that have beta-lactam ring.
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What are 3 meds that have beta-lactam ring and can be combined with beta-lactams to treat organisms with beta-lactamase?
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Clavulanate, Sulbactam, Tazobactam
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What are 4 types of abx that inhibit bacterial protein synthesis?
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Aminoglycosides, MLS drugs, Tetracyclines, Glycyclines (newer)
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What are the 3 MLS drugs?
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Macrolides (Ketolides), Lincosamides, Streptogramins (not in US)
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What are two antibiotics that inhibit bacterial DNA synthesis?
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Quinolones, Nitromidazole
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What is an antibiotic that inhibits bacterial RNA synthesis?
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Rifamycin
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What are two antibiotics that are anti-folates?
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Sulfonamides, Trimethoprim-Sulfamethoxazole
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How are abx that affect bacterial wall synthesis usually metabolized/excreted? Based on this, what type of infection might they be good for?
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Excreted through kidneys. Might be good to use for UTIs
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What has been a problem with aminoglycosides? What specific aminoglycoside is still used?
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Had toxicity causing renal problems and decreased hearing.
Gentamycin still used |
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What is a downside to the longer half life of doxycycline vs tetracycline?
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If toxicity occurs, it lasts longer
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What is Rifamycin/Rifampin commonly used for? (affects bacterial RNA synth)
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Used for TB or as a chemoprophylaxis for TB. Also N. meningitidis
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What is a common side effect of Rifamycin/Rifampin?
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Turns all body fluids orange Should warn patients about this.
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What is the most allergenic drug and therefore not used as much anymore?
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Sulfonamides
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What are drug factors that might affect patient response?
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Wrong drug, dose or route
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What are bug factors that might affect patient response?
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Drug-resistant organism, superinfection or multiple organisms
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What are host factors that might affect patient response?
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Pus or foreign body, poor pt compliance
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What are agricultural contributing factors to resistance?
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Animal growth promotion, spraying fruit trees, absorption of abx in plants meant for food
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What are the 12 steps to prevent resistance? CDC
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1. Vaccinate. 2. Remove caths 3. Target pathogen. 4. Access experts 5. Antimicrobial control programs. 6. Use local data. 7. Treat infection, not contam. 8. Treat infection not colonization. 9. Know when not to use vanco. 10. Stop unnecc abx treatment. 11. Isolate path. 12. Break chain of infection
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What accounts for most resistance?
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Acquisition of resistance genes or gene clusters via conjugation, transposition or transformation
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What is a definition of a virus?
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Non-living obligate intracellular parasite - inert when extracellular
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Why are viruses unable to replicate on their own?
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Do not have ribosomes, lack genes and enzymes needed for energy, must use host ribosomes, enzymes and metabolites for protein and nucleic acid production
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What life forms can viruses effect?
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Humans, animals, plants and bacteria
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What is a virion?
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One virus particle (not a cell). Small: 20-300nm. Genetic info surrounded by delivery system
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What is the structure of a virus?
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Nucleic acid core (RNA or DNA) wrapped in protein capsid and either enveloped (naked) or non-enveloped
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What are the various nucleic acid structures in the viral genome?
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circular, linear or segmented
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What are the functions of the protein capsid around viruses?
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Protection from chemical, physical threats, shape determination, attachment
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What are the subunits of viral protein capsids and what are their functions?
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Capsomeres. Arrangement allows for identification and classification of the virus. Also, it is antigenic.
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What is a helical shape capsid arangement and what type of nucleic acids?
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spiral staircase w/ genome in middle. ALWAYS RNA
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What is an envelope?
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Acquired during budding after viron assembled in host cell. Made from lipids and carbs from membrane of host cell. Also contains virus-specific proteins.
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Does an envelope make the virus more fragile or less fragile?
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More fragile - suscep to heat, detergents, alcohols and proteolytic enzymes.
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What is an example of an enveloped virus?
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Herpes - enveloped from nuclear membrane.
Droplet infections tend to be enveloped (influenza) |
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What type of viruses tend to be non-enveloped?
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GI viruses
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What are spikes (peplimers)?
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Glycoprotein projections which bind specific receptors on host cell
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Where are the enzymes viruses might have?
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May be on surface (influenza) or inactive in the core. But usually they use host enzymes.
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How does viral classification help us?
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Helps to make predictions about replication, pathogenesis and transmission
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What are the 4 things used for classification of viruses?
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Type of nucleic acid (DNA or RNA; single or dbl), Ultrastructure of virus particle, Strategy for gene replication, Immunologic properties
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What are 4 things that help determine the ultrastructure of a virus?
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Size, symmetry of capsid, # of capsomers, envelope or naked
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What are the 4 practical naming strategies and an example of each?
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For disease caused: polio virus, For body system: hepatitis, For route of transmission: arbovirus by arthropods, For shape: rotovirus
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What 4 host defenses much GI viruses overcome to causes illness?
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High acidity, bile salts (destroy viral envelopes), enzyme activity, mucosal barrier
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What is iatrogenic transmission?
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Transmission via a health care provider. Ex: transfusions
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What contributes to a PERMISSIVE host cell?
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Viral receptors, enzymes for replication
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What is tropism?
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Ability of a virus to replicate in particular cells or tissue
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What controls tropism?
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The route of infection, interaction of virus w/ a specific receptor on the surface of host cell, has effect on pathogenesis
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What are the 4 stages of virus reproduction?
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Attachment & penetration, uncoating, macromolecular synthesis, assembly & release
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Does attachment (in viral reproduction) require energy?
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No
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What is virus attachment protein (VAP)?
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Specific area for attachment virion to a variety of receptors on permissive host cell.
Enveloped: attach via spikes. Non-enveloped: exposed VAP |
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What is viral incubation period?
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Period btwn viral cell attachment and clinical symptoms
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What happens in penetration (uptake) of viral reproduction?
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Translocation of viral genome across host membrane, occurs rapidly after attachment.
Different viral types use diff techniques |
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How do non-enveloped viruses penetrate host cell?
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Translocation of entire virus across host membrane. Endocytosis (common). or entrance w/out vacuole formation
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How do enveloped viruses penetrate host cell?
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Fusion of viral envelope w/ host cell membrane
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What is uncoating that occurs during viral reproduction?
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Removal of the delivery system, makes viral nucleic acids avail to host cell transcription and translation machinery, often happens simultaneously w/ penetration
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Is the phase of uncoating the best time to detect disease?
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No. It is difficult to detect disease during this stage. No intact virus can be detected and no new virions are being produced.
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What takes place during biosynthesis of macromolecules in viral reproduction?
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Nucleic acids and proteins of virions are manufactured.
Viral mRNA must be made to allow for translation of viral proteins. |
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What occurs during DNA replication?
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DNA polymerase facilitates making DNA copy
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What occurs during transcription?
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RNA polymerase facilitates making of mRNA from DNA
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What occurs during translation?
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Ribosomes decode mRNA to make proteins
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How is mRNA made from double-stranded DNA virus and single stranded DNA virus?
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Uses HOST cell RNA polymerase to create mRNA
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How is mRNA made from double stranded RNA or single stranded RNA virus?
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Viral RNA polymerase. Must be viral encoded.
mRNA created from negative strand of double strand via transcription. |
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What are the two types of single-stranded RNA viruses?
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Positive Sense and Negative Sense
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What is Positive Sense RNA?
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5' to 3' already so can be directly translated into viral proteins w/out being transcribed first. Does not need RNA polymerase.
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What is Negative Sense RNA?
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3' to 5'. Must be converted to positive sense RNA by VIRAL encoded RNA polymerase via transcription. Then positive sense = mRNA and can be translated to proteins.
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What is the process of reverse transcription?
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Retrovirus - +RNA virus that gets reverse transcribed into double stranded DNA so that it can become integrated into the host cells genome. Uses HOST cell RNA polymerase.
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What are early proteins in biosynthesis of macromolecules?
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Enzymes
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What are late proteins in biosynthesis of macromolecules?
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Structural
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If viral infection does not occur at the site of entry (non-permissive cells), how would the virus spread?
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Neural spread, Hematogenous spread, or both
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How are non-enveloped viruses released from host cell?
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Lysing host cell (viral burst) - associated with host cell death
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How are enveloped viruses released from host cell?
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Through budding. Sometimes causes host cell death.
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What are the 4 ways viral replication can effect host cell?
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Host cell death - inhibition of cellular protein production, Fusion of virus-infected cells to form multinucleated cells, malignant transformation, or no apparent affect
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What kind of virus usually causes latent infection? What occurs during latency?
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Usually DNA virus. During latency, no progeny virus produced.
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What occurs during chronic viral infection?
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Virus is produced, but in less amounts
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What occurs in a viral carrier state?
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Significant amount of virus is produced for a long period of time.
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What is a slow virus?
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Virus in which there is a prolonged period btwn initial infection and disease.
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What are two innate forms of host response to virus?
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Interferons, complement
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What are two adaptive host responses to virus?
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Cell-mediated (NK cells), Humoral (antibody response)
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What do interferons do beside interfere with viral protein synthesis? What is a virus that we use interferons to treat?
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Also activate host macrophages and NK cells.
Hep C |
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What does the classical complement pathway do to viruses? Alternative pathway?
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Classical: opsonize virus to enhance phagocytosis.
Alternative: lysis of enveloped viruses or virus-infected cells. |
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What is the most important adaptive mechanism for viral defense?
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Cell-mediated.
Lysis of virus infected cell by lymph cells. |
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What is one of the earliest host defenses against viruses?
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NK cells
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What cells lyse antigen-presenting cells infected by a virus?
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Cytotoxic T lymphs (killer T)
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What are 3 virus virulence factors?
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Inhibit interferon, inhibit complement (HSV), change surface markers to inhibit immune system recognition (Adenovirus)
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What are 4 types of antiviral therapy?
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DNA polymerase inhibitors, reverse transcriptase inhibitors, ion channel blockers (stops membrane disruption), protease inhibitors
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What is an example of an antiviral therapy that inhibits DNA polymerase?
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Acyclovir
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What is an example of an antiviral therapy that inhibits reverse transcriptase?
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Azidothymidine (AZT)
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What is an example of an antiviral therapy that blocks ion channels?
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Rimantadine (flumadine)
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What is an incomplete ("defective") virus? What's an example?
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Naked RNA w/out capsid. Hep D. Can't cause infection alone, can only infect with Hep B
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What are Prions?
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Infectious agents made purely of protein. No nucleic acids, direct ingestion, protein folding of prion causes host infection.
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What is an example of a Prion?
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Bovine Spongiform Encephalopathy (aka mad cow disease)
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What is an attenuated virus?
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Lost ability to cause disease in immunocompetent. Used for some vaccines.
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What is the family that influenza A belongs to? What type of virus is it?
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Orthomyoxoviridae.
Negative sense RNA virus |
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What are the two subtypes of Influenza A?
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Hemagglutin (H number 1-16) and Neuraminidase (N number 1-9)
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What does hemagglutin (H number) of influenza A do?
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Responsible for binding virus to cell receptor.
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What does neuraminidase (N number) of influenza A do?
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Enzyme involved in virus release from host cell. Cleaves hemagglutin-sialic acid bond.
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What is the makeup of H1N1?
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Reassortment of 4 known strains of influenza A. Mixing of genetic material of one strain in humans, one in birds, two in pigs.
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What is the infectious course of H1N1?
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Infectious 1 day before symptoms and 5-7 days after
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How would you treat high risk patients with H1N1?
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Tamiflu (oseltamivir), Relenza (zanmivir)
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What are the target groups for Influenza A vaccine?
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Preg, 6mos-24 yrs, caregivers of kids <6 mos, healthcare workers, aged 25-64 w/ high risk medical conditions.
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