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Micro lecture 16
| Question | Answer |
|---|---|
| Name some examples of Gram-positive rods | Bacillus, Clostridium, Listeria, Corynebacteriu, Nocardia, Mycobacterium, Actinomyces, Propionibacterium |
| Name some characteristics of Bacillus | Aerobic or facultative anaerobic; spore-forming; large; Gram-positive rods in pairs or chains; usually catalase positive; move by peritrichous flagella |
| What does B. cereus look like on a BAP? | large with a dull or frosted-glass surface and undulate margin. Beta-hemolysis |
| What does B. cereus do? | Ocular infections; destroys eye. Or, gastroenteritis for food poisoning. |
| What are the forms of B. cereus gastroentiritis? | Diarrheal and Emetic (causing vomiting) |
| What are the characteristics of B. anthracis? | nonmotile, capsule needed for full virulence |
| What is the anthrax exotoxin made of? | 3 plasmid-encoded polypeptides. (AB exotoxins) |
| What are the 3 anthrax exotoxins? | Protective antigen, Lethal toxin (lethal factor + protective antigen), edema toxin (edema factor + protective antigen) |
| What are the 3 ways B. anthracis is transmitted? | Cutaneous (causes eschar/skin necrosis), Inhalation (takes a while, spores inhaled, flu-like symptoms), and Ingestion (rare in humans, common in herbivores, high mortality rate due to blood loss and intestinal perforation). |
| Clostridium characteristics | Anaerobic, spore-forming, large, mostly Gram-positive rods |
| Examples of Neurotoxic Clostridium spp. | C. botulinum (botulism), C. tetani (tetanus) |
| Examples of Histotoxic Clostridium spp. | C. perfringens (myonecrosis, gas gangrene), C. septicum (malignant edema) |
| Examples of Enteric Clostridium spp. | C. perfringens (enteritis, enterotoximia), C. difficle (diarrhea, pesudomembranous colitis), C. piliforme (Tyzzer's disease) |
| How many toxins does C. perfringens produce? | a lot - 10 exotoxins and 2 enzymes. All produce α-toxin, which lyses RBCs, WBCs, and endothelial cells. |
| Clostridial food poisoning is an example of an ________. | intoxication |
| What are C. difficle's two toxins? | Toxin A and Toxin B |
| What is C. difficle's Toxin A? | An enterotoxin. Causes diarrhea |
| What is C. difficle's Toxin B? | A cytotoxin. Disrupts actin cytoskeleton of GI lining cells. |
| What does C. difficle cause? | Colitis |
| Some clostridia are Gram-negative in an ___________ environment. | aerobic. This means you have to also test in an anaerobic environment to ensure accurate ID. |
| What does C. piliforme cause? | Tyzzer's disease. Messes with the intestines. |
| C. piliforme can only grow ________ __ _____. | inside of cells |
| What does C. piliforme look like? | Bundles in liver cells (hepatocytes) |
| What is a good way to clean up C. piliforme spores/bacteria? | A 1/10 dilution of household bleach and water. |
| Name 2 noninvasive clostridia | C. botulinum, C. tetani |
| What does botulism do? | Infects kids only, progressive paralysis of skeletal muscles. It cleaves the neurotransmitter release protein on motor nerve terminals. |
| What does tetanus do? | Blocks inhibitory neurotransmitters on motor neurons, causing, for example, both the triceps and the biceps to contract instead of the biceps to be relaxed. |
| Characteristics of Listeria | Aerobic, non spore-forming, short, Gram-positive rods; catalase positive |
| Where can listeria grow? | In refrigerated foods derived from animal sources |
| What are the most commonly reported forms of listeriosis? | Septicemia and meningitis |
| L. monocytogenes is one of the most important causes of what in humans? | Food-borne illness. This causes meningitis. |
| How does listeria avoid the immune system? | It survives inside macrophages; it organizes actin to move around within and between cells. |
| Characteristics of Corynebacterium | Aerobic, Gram-positive, non spore-forming, pleomorphic rods |
| Why is the Corynebacterium cell wall interesting? | An anarabinogalactan layer is attached to it and small hydrophilic molecules can go through passages. It lets the cell survive under adverse conditions. |
| What 3 Corynebacterium species may be toxigenic? | C. diptheriae, C. pseudotuberculosis, C. ulcerans. All 3 can produce diptheria toxin when lysed by corynephage beta bearing tox gene. |
| What does the Diptheria toxin do? | inhibits protein synthesis in host cells |
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