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52 Cards in this Set
- Front
- Back
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Bacillus anthracis appears like what on culture?
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Ground-glass appearance and are nonhemolytic on sheep blood agar, nonpigmented, edge-irregular with comma projections (Medusa head colonies).
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What are the four bacilli gram positive?
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Bacillus, Clostridium, Listeria, and Corynebacterium
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Of the four bacilli gram positive, which two are spore-forming rods?
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Bacillus and Clostridium
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Between Bacillus and Clostridium, which one is anaerobic?
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Clostridium
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What are the species belonging to Bacillus?
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B. cereus and B. anthracis
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Between B. cereus and anthracis, which one is motile?
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B. cereus
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What is unique about Bacillus anthracis?
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The only bacteria with a capsule composed of protein (glutamic acid), which prevents phagocytosis.
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When are humans exposed to B. anthracis?
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When exposed to spores in contact with infected animals (goat, cow, other herbivore--including hides or wools), and soil.
US cases: PTs handling goat hair products, such as drums or rugs |
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What are the means of spore germination from Bacillus anthracis in humans?
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Skin abrasions, lung inspiration, and ingestion into GI tract.
Note: once germinated, it makes toxins Uncontrolled bacteremia leads to meningitis |
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Ulcer caused by anthrax looks like?
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The ulcer has a painless blackened necrotic eschar surrounded by edema. Prior to ulcer, may appear as a painful, small red macule.
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What happens with a cutaneous abrasion with anthrax?
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Exotoxin causes localized tissue necrosis, evidenced by a painless round black lesion with a rim of edema, called "black eschar". This is caused by LF and EF.
Note: most common form of anthrax |
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Ingestion of anthrax can cause?
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Necrotic lesions, dysentery, bloody diarrhea.
Frequently results in death. This form is rare |
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Inhalation of anthrax can cause?
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Mediastinal hemorrhage and widening, pulmonary hemorrhage, pleural effusion, fever, dyspena.
High mortality rate. Note: Macrophages carry the spores to tracheobronchial or mediastinal lymph nodes. |
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What are the exotoxin of B. anthracis?
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Edema factor: increases cAMP, which impairs neutrophil function and causes massive edema, such as mediastinal edema.
Protective antigen: promotes entry into phagocytic cells Lethal factor: zinc metalloprotease that inactivates protein kinase. Stimulates macrophage to release TNF and IL-1, which contributes to death. Also causes hemorrhagic necrosis in lymph nodes, resulting in the release of large numbers of B. anthracis. Nonspecific flu-like illness develops. |
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Treatment of B. Anthracis?
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Ciprofloxacin is the DOC or doxycycline.
There is also a vaccine, anti-protective antigen. |
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Bacillus cereus infection can be caused by?
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Uncooked food (e.g., rice)
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What does B. cereus cause?
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Food poisoning (emetic syndrome or diarrheal syndrome)
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What causes emetic syndrome of B. cereus? And what is it similar to?
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Heat-stable enterotoxin, which is stimilar to S. aureus food poisoning: short incubation period, severe nausea, vomiting, and limited diarrhea occurring 1 - 5 hours after ingestion..
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What causes diarrheal syndrome in B. cereus?
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Heat-labile toxin, similar to enterotoxin of cholera and LT from E. coli: nausea, abdominal pain, diarrhea occurring 12 - 24 hours after ingestion.
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What antibiotics do you use to treat the food poison from B. cereus?
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You don't since this is caused by an enterotoxin. Rehydrate the PT.
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Out of Clostridium botulinum, tetani, difficile, and perfringens, which one is non-motile?
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C. perfringens.
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Out of Clostridium botulinum, tetani, difficile, and perfringens, which ones are obligate anaerobe?
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All of them.
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What does C. botulinum produce? And what are the symptoms?
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The most potent toxin, a neurotoxin that blocks acetylcholine causing flaccid muscle paralysis.
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How is adult botulinum obtained?
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Eating smoked fish or home-canned vegetables in an anaerobic environment.
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How do you treat Botulism
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Antitoxin and respiratory support.
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Course of infection of botulism?
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CN involvement (diplopia, dysarthria, dysphagia) --> m. paralysis --> respiratory paralysis and death.
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Infant botulism occurs how? And what is Floppy Baby Syndrome?
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Spores often in honey. Constipation, flaccid paralysis.
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How is Clostridium tetani usually obtained?
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Wound puncture, such as by a rusty nail. C. tetani spores are usually in soil and animal feces.
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What is C. tetani exotoxin called? How does it work?
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Tetanospasmin, which blocks inhibitory Renshaw cell interneurons to prevent the release of GABA and glycin--both of which, are inhibitory neurotransmitters.
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Does C. tetani cause flaccid or contracted muscles?
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Causes sustained contraction of skeletal m.
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What is Risus sardonicus?
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Grotesque grinning due to spasm of the facial m.
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What is the prophylaxis of C. tetani?
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DTaP
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When lockjaw happens from C. tetani, what does that represent?
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A high mortality. PTs die from respiratory failure.
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What is the treatment of C. tetani?
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Penicillin, metronidazole, diazepam (GAMA agonist), clean wound, antitoxin.
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Gas gangrene (myonecrosis with crepitus) is caused by? And what proteins are released?
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Clostridium perfringens, which can release alpha toxin (lecithinase) that has phospholipase C activity on cell mm and degradative enzymes.
Crepitus: palpation will reveal moist, spongy, crackling consistency to the skin from pockets of gas. Enzymes ferment carbohydrates to gas. There will be a blackish fluid exudate form the skin. |
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How is C. perfringens obtained?
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Spores found in soil that matures in anaerobic conditions (wounds from battle or trauma) and produces gas.
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What can C. perfringes cause?
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Cellulitis (via collagenase, hyaluronidase), gas gangrene, and food poisoning.
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What is the treatment of C. perfringens?
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Penicillin, (clindamycin in local, weak infections), hyperbaric oxygen, and removal of infected area.
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What causes pseudo-membranous coliitis (diarrhea).
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Clostridium difficile due to broad spectrum antibiotics, wiping out the normal intestinal flora. This allows overgrowth of C. difficile.
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What are the toxins of C. difficle?
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Toxin A (watery diarrhea) and Toxin B (pseudomembrane).
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How do you diagnosis C. difficile?
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Toxin B in stool, and upon colonoscopy, pseudomembranes (yellow-white plaques--necrosis of mucosal surface underneath).
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How is a base site selected?
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Selection of base site should be within an area which can be defended by all available forces and provide mooring for ships and craft. Be within operational and comm. range of deployed element
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Other than denoting that Clostridium botulinum is Gram + rod and anaerobic, and checking for toxin in uneaten food, how else can you diagnose botulism?
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Mouse test: inject serum into mouse and check for paralysis/death.
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What drug usually causes pseudomembrane colitis?
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Often, clindamycin or ampicillin
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What drug can you use to treat pseudomembrane colitis?
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Metronidazole or vancomycin (not absorbed, act on intestinal bacteria)
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What is a further complication caused by gangrenous muscle?
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Black fluid exudate leaking from skin, with shock possibly following.
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What is a positive proof for a toxigenic isolate (of C. perfringens)
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Positive lecithinase on egg-yolk agar, neutralized by antitoxin.
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Clostridium species are found?
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In the normal human flora. C. perfringens cause disease only when they leave their normal niche (colon).
Clostridial spores are found in the soil. |
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What elevates the risk for anaerobic infection?
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Vascular stasis.
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What is the common genesis of C. perfringens infection?
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Bowel surgery allows anaerobes and facultative anaerobes access to tissue outside the colon. Facultative anaerobes assist the primary anaerobes to proliferate outside the colon by creating a growth environment with low oxygen potential.
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Isolation of Clostridium septicum from the blood indicates?
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Colon cancer or leukemic cecitis.
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What is the treatment for C. perfringens?
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Surgical drainage and debridement. O2 therapy?
DOC: penicillin. Broader spectrum: metronidazole (anaerobes only), clindamycin, piperacillin/tazobactam, imipenem/cilastatin, or meropenem. |
