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51 Cards in this Set
- Front
- Back
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What are the 2 'families' of Gram positive rods that form a spore? What is the difference between them?
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Bacillus = aerobic
Clostridium = anaerobic |
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What are the two most significant members of the Bacillus genus? Disease-associations?
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B. anthracis = causes anthrax
B. cereus = food-borne diarrheal disease |
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What are 4 members of the clostridium genus? Disease associations?
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C. perfringens = necrotizing skin and soft tissue infections
C. difficile = hospital-acquired diarrheal disease C. tetani = tentanus C. botulinum = botulism |
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What are the 2 major families of non-spore forming, non-filamentous gram positive rods?
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Corynebacterium
Listeria |
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What are 2 members of the Corynebacterium family? Disease associations?
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Corynebacterium diptheraie = toxin-mediated disease of upper airways and skin
Other Corynebacterium = bacteremia w/ foreign bodies |
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What are 2 members of the Listeria family? Disease associations?
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Listeria monocytogenes = self-limiting diarrhea, can spread to cause bacteremia, meningitis, infections of fetus
Prpionibacterium acnes and Erysipelothrix rhusiopathiae = minor infections |
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B. anthracis
a. aerobic/anaerobic? b. nonspore/spore? c. motility?d. hemolytic? e. habitat |
a. aerobic
b. spore c. non motile d. non hemolytic e. soil |
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What are 3 clinical syndromes of anthrax and how is each contracted?
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1. Cutaneous = spores implant through skin trauma
2. GI = eating contaminated meat 3. Inhalation = intake of aerosolized spores |
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What are 3 virulence factors of b. anthracis?
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1. Poly-glutamic acid capsule = anti-phagocytic
2. Ability to survive within macrophages 3. 3 secreted toxins (edema toxin, lethal toxin, protective antigen) |
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How does inhalation anthrax acquired? What happens next? (general)
What are the disease implications? |
Pulmonary macrophages engulf spores but don't kill --> take them to Lymph nodes --> spores germinate and secrete toxins
bacteremia, accumulations in ECF --> hemorrhage |
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What do the three toxins secreted by b. anthracis do?
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1. PA = carrier molecule, binds to surface of mammalian cell
2. EF = calmodulin-dependent AC --> increase cAMP, interferes with production of cytokines, causes leakage of fluid from vessels 3. LF = MAPK kinase, interferes with normal intracellular signaling and inflammatory rxns --> cell can't control growth |
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What are 2 drugs that are used to treat B. anthracis?
Why does penicillin not work? |
doxycycline, ciprofloxacin
B. anthracis contains genes for a penicillinase and a cephalosporinase (B-lactamases) |
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B. cereus
a. spore? b. aerobic? c. habitat? |
a. Yes
b. Yes c. soil, grains/cereals, GI of herbivores |
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What are two syndromes caused by b. cereus?
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Emetic and Diarrheal
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How does emetic syndrome from b. cereus occur?
Incubation time? |
Heat stable toxin produced from spores on inadequately heated/refrigerated food (spores not killed on cooking) --> ingest pre-formed toxin
Incubation is 1-6 hours |
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How does the Diarrheal disease from b. cereus occur?
Incubation time? |
Food with spores in it (meat, cream) inadequately heated/refrigerated --> spores ingested --> secrete heat-labile toxin in GI
Incubation = 24 hrs (time for cell growth in intestine) |
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How can one tell in the lab between b. anthracis and other bacillus species?
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b. anthracis = nonmotile, non hemolytic
other bacillus species are motile and hemolytic |
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C. perfringens
a. Shape? b. Aerobic? c. Spore? d. Habitat |
a. Rectangular, large
b. anaerobic c. spore forming d. soil, GI |
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What are the five types of c. perfringens? 3 disease associations?
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Type A-E
Type A = in soil --> gas gangrene Types B-E = GI of animals (not humans) Type C = necrotizing enterocolitis |
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What is the mechanism of virulence for c. perfringens?
What is the most common toxin secreted and what does it do? (4) |
Secrete many toxins
Type A --> alpha toxin --> PLC to disrupt membranes, hemolysin, kills endothelial cells to increase vascular permeability, causes necrosis |
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What is gas gangrene?
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Trauma allows penetration of c. perfringens --> cellulitis, growth of bacteria in dead tissue, secretes toxins --> necrotizing fasciitis, suppurative myositis, myonecrosis
No inflammation because toxins lyse WBCs entering tissue |
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What is clostridial food-borne gastroenteritis?
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Ingestion of inappropriately re-heated meat infect with c. perfringens --> spores secrete heat-labile toxin --> abdominal cramping, watery diarrhea, incubation < 24 hrs
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What is necrotizing enterocolitis?
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Meat contaminated with c. perfringens --> beta toxin secreted --> tissue necrosis in bowl --> intestinal perforation, peritonitis, shock
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C. difficile
a. aerobic? b. spore? c. habitiat d. Disease association? |
a. anaerobic
b. spore forming c. normal GI flora d. Diarrhea - nosocomial and Ab resistent |
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What are the virulence factors in c. difficile that cause diarrhea?
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Toxin A = enterotoxin --> fluid secretion in intestine
Toxin B = cytotoxin --> kills intestinal epithelial cells --> pseudomembrane |
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What is the pathogenesis of c. difficile associated diarrhea?
What are the symptoms? |
Ab therapy --> opportunistic infection by c. difficile (normal part of GI flora) --> release toxin A and B --> colonic mucosal injury and inflammation
Diarrhea, abdominal pain, nausea, fever |
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How does c. tetani infect?
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Enters on a puncture wound, grows in anaerboic environment created by dead tissue (from puncture wound) --> germinates --> secretes tetanospasmin toxin
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What is the virulence factor for c. tetani? How does it work?
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toxin tetanospasmin
Heavy chain binds to GABA inhibitory neurons in CNS and spinal cord Light chain = endopeptidase, cleaves synaptobrevin (for exocytosis of vesicles), so NT cannot be released in vesicles --> loss of descending inhibition --> spastic paralysis |
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What are 3 sources of c. botulinum?
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1. Food-borne - home-canned food products
2. Infant botulism from raw honey ingestion 3. Wound botulism from heroid |
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c. botulinum
a. spore? b. aerobic? c. habitat |
a. Spore
b. anaerobic c. soil |
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What causes food-borne infection of c. botulinum?
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spores heat stable but toxin is heat labile --> inadequate refrigeration allows germination --> inadequate heating allows toxin secretion --> ingest pre-formed toxin
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What are the virulence factors in c. botulinum?
What does this cause? |
botulinum toxin
Heavy chain binds to peripheral cholinergic synapses Light chain = endopeptidase, prevents release of Ach at NMJ Flaccid paralysis |
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Corynebacterium diphtheraie
a. Aerobic? b. spores? c. habititat |
a. aerobic
b. non spores c. skin, resp tract |
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How does corynebacterium diphtheraie become virulent?
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normally avirulent, but becomes virulent when it acquires the toxin gene from a lysogenic phage
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How is diphtheraie spread from person to person? What could stop the spread?
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Skin contact, nasopharyngeal secretions, inanimate objects
Immunization |
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What is the virulence factor of corynebacterium diphtheriae?
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Toxin
B fragment binds to cell surface receptors A fragment ADP ribosylates EF2--> inhibits protein synthesis of host cell --> pseudomembrane in throat, obstruction |
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Where can diphtheraia infection strike and what are its effects?
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Throat, can form pseudomembrane --> respiratory obstruction
Can spread to heart and nervous system --> EKG abnormalities, circulatory failure, neuritis, respiratory failure |
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How can diphtheria be treated?
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Equine antitoxin and Antibiotics
Vaccine |
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Where do other corynebacterium species lie? What is their effect?
What is one exception |
Skin flora --> no disease, but can contaminate blood culture
Corynebacterium jeikeium can infect medical devices, highly Ab resistent --> treat with vancomycin |
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Listeria monocytogenes
a. spore? b. motility? c. aerobic? d. hemolysis? e. where does it grow in body f. habitat |
a. non-spore
b. tumbling motility c. aerobe, but can grow anaerobically (has catalase); d. b-hemolytic e. facultative intracellular bacteria - grows well in macrophage cytoplasm f. food - deli meat, cheese |
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What are some manifestations of infection with listeria species?
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Diarrhea
Meningitis in immunocompromised infections in fetus if pregnant |
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What is the meaning of listeria being a facultative intracellular bacteria? How does it do this?
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Grows well in macrophage cytoplasm
Induces macrophage internalization, then secretes listeriolysin O to allow bacteria to escape into cytoplasm |
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What is the drug of choice for listeriosis?
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ampicillin
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Propionibacterium acne
a. aerobic? b. virulence c. habitat d. disease associations |
a. anaerboic
b. saprophytic commensals, not normally virulent c. skin -- can cause blood culture contamination d. acne |
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How can diphtheria be treated?
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Equine antitoxin and Antibiotics
Vaccine |
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Where do other corynebacterium species lie? What is their effect?
What is one exception |
Skin flora --> no disease, but can contaminate blood culture
Corynebacterium jeikeium can infect medical devices, highly Ab resistent --> treat with vancomycin |
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Listeria monocytogenes
a. spore? b. motility? c. aerobic? d. hemolysis? e. where does it grow in body f. habitat |
a. non-spore
b. tumbling motility c. aerobe, but can grow anaerobically (has catalase); d. b-hemolytic e. facultative intracellular bacteria - grows well in macrophage cytoplasm f. food - deli meat, cheese |
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What are some manifestations of infection with listeria species?
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Diarrhea
Meningitis in immunocompromised infections in fetus if pregnant |
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What is the meaning of listeria being a facultative intracellular bacteria? How does it do this?
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Grows well in macrophage cytoplasm
Induces macrophage internalization, then secretes listeriolysin O to allow bacteria to escape into cytoplasm |
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What is the drug of choice for listeriosis?
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ampicillin
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Propionibacterium acne
a. aerobic? b. virulence c. habitat d. disease associations |
a. anaerboic
b. saprophytic commensals, not normally virulent c. skin -- can cause blood culture contamination d. acne |
