Term
| Three things that contribute to virulence (degree of organism pathogenicity) |
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Definition
1. cell structures
2. exotoxins
3. endotoxins |
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Term
| Cell structures as virulence factors ( |
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Definition
| Flagella, pili (fimbriae), capsules, endospores, biofilms |
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Term
| The movement towards/away from chemical concentration gradient? |
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Definition
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Term
| Vibrio cholera has what kind of flagella? |
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Definition
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Term
| Escherichia coli and Proteus mirabilis have what kind of flagella? |
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Definition
| many peritrichous flagella (all around the cell) |
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Term
| Where are periplasmic flagella found? |
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Definition
| Under outer membrane sheath in spirochetes |
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Term
| How are pili different from flagella? |
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Definition
1. Much shorter
2. Do not move |
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Term
| What gives pili virulence? |
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Definition
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Term
| What are protective walls that surround the cell membranes of gram (+) and (-) bacteria made of simple sugar residues? |
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Definition
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Term
| Which bacterium has its capsule made of AA residues? |
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Definition
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Term
| What gives capsules virulence? |
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Definition
| Macrophages and neutrophils cannot phagocytize bacteria with capsules (e.g. Streptococcus pneumoniae) |
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Term
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Definition
| Antibodies binding to the capsules of bacteria |
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Term
| Two tests to visualize capsules under microscope |
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Definition
1. India ink stain (capsules don't take up dye, looks like halo around the cell)
2. Quellung reaction (Ab binds to the capsules, which swell with water) |
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Term
| 2 bacterial genera that form "endospores" |
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Definition
1. bacillus (gram+ rod, aerobic)
2. clostridium (gram+ rod, anaerobic) |
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Term
| What are endospores resistant to? |
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Definition
| heat (boiling), cold, drying, chemical agents |
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Term
| Multilayers that give endospores virulence (resistance to enviornment) |
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Definition
* a cell membrane
* a thick peptidoglycan mesh
* another cell membrane
* a wall of keratin-like protein
* exosporium (outer layer) |
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Term
| Which species forms biofilms (extracellular polysaccharide network) in catheters? |
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Definition
| Staphylococcus epidermidis |
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Term
| Facultative intracellular organisms (safe from antibodies) |
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Definition
- Listeria monocytogenes
- Salmonella typhi
- Yersinia
- Francisella tularensis
- Brucella
- Legionella
- Mycobacterium |
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Term
| Which gram (+) genus does NOT secrete exotoxins? |
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Definition
| Listeria monocytogenes (endotoxin) |
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Term
| Diseases caused by bacterial exotoxins |
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Definition
| anthrax, botulism, cholera, tetanus |
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Term
| What are neurotoxins and examples? |
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Definition
- exotoxins that act on the nerves or motor endplates to cause paralysis
- tetanus, botulism |
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Term
Enterotoxin
- definition
- three mechanisms? |
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Definition
- exotoxins that act on the GI tract to cause diarrhea
- Inhibit NaCl resorption, activate NaCl secretion, kill intestinal epithelial cells |
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Term
| 2 disease manifestations by enterotoxins (& examples) |
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Definition
1. infectious diarrhea (Vibrio cholera, E coli, Campylobacter jejuni, Shigella dysenteriae)
2. Food poisoning (Bacillus cereus, Staphylococcus aureus) |
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Term
Pyrogenic exotoxins
- function
- examples |
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Definition
- stimulate the release of cytokines; cause rash, fever, and toxic shock syndrome
- Staphylococcus aureus, Streptococcus pyogenes |
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Term
| Exotoxin subunits in Bacillus anthracis, Clostridium botulinum, Clostridium tetani, Corynebacterium diphtheriae, Vibrio cholera) |
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Definition
| 2 polypeptide subunits: B(binding)/H(holding)--two disulfide bonds--A(action)/L(laser). B/H: binds to the cell, A/L: enters the cell and exerts toxic effect |
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Term
| Why can treating a pt with gram(-) infection with antibiotics can worsen the symptoms? |
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Definition
| As bacterial cells are lysed, endotoxin/lipid A (part of outer membrane) is released |
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Term
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Definition
| Bacteremia (bacteria in blood) that causes a systemic immune response to the infection. |
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Term
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Definition
- high/low temperature
- high WBC count
- faster HR/RR |
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Term
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Definition
- sepsis that results in dangerous drops in blood pressure and organ dysfunction
- endotoxic shock (septic shock is usually caused by endotoxins, but gram+ and fungi cause as well) |
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Term
| Immune cells (macrophages, PMNs) release ______ _______ as response to endotoxins/exotoxins in the blood. |
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Definition
| endogenous mediators (proteins) |
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Term
| Molecular mechanism of septic shock |
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Definition
| bacteremia --> immune cells (Macrophages, PMNs) secrete endogenous mediators such as TNF (=cachectin) --> cytokine interleukin-1 is released from macrophages and endothelial cells --> prostaglandins are released --> vasodilation, hypotension, organ system dysfunction |
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Term
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Definition
1. Empiric antibiotics therapy (early)
2. Maintain blood pressure (dopamine, norepinephrine)
3. Oxygenation (intubation, mechanical ventilation)
4. hydrocortisone (a corticosteroid IV) |
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