Term
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Definition
- gram-, non-spore forming rods
- capsule or slime layer
- motile or non-motile
- pili for attachment
- speciated by carbohydrate fermentation tests
- cause diarrhea, dysentery, typhoid fever, hemorrhagic colitis, UTIs, septicemia, pneumonia, meningitis
- Ag structure
- K Ag - mucopolysaccharide
- O Ag - LPS
- H Ag - flagellin protein
- Determinants of pathology
- endotoxins - lipid A portion of LPS ---> fever, shock
- enterotoxins - affect small intestine to cause transduction of fluid into lumen --> diarrhea
- Laboratory diagnosis
- grow in air to eliminate anaerobes
- carbohydrate fermentation tests: MacConkey, Hektoen agar
- serology: O, H, K Ag
- PCR
- Escherichia
- Shigella
- Salmonella
- Proteus
- Klebsiella
- Enterobacter
- Serratia
- Citrobacter
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Term
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Definition
- gram-, halophilic, non-spore forming curved rods
- highly motile, oxidase+
- cause cholera, gastroenteritis, septicemia, wound infections, peptic ulcers, diarrhea
- LPS (O Ag) important
- Vibrio
- Campylobacter
- Helicobacter
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Term
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Definition
- motile, lactase+, oxidase- no H2S production
- facultative anaerobe
- grow on MacConkey agar (bile salts inhibit gram+)
- pathogenesis (genes carried on plasmids)
- adhesins
- heat labile toxin --> binds AC --> ↑ cAMP + fluid loss
- heat stable toxins --> bind to GC --> ↑cGMP + fluid loss
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Term
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Definition
- gram-, comma shaped, never normal flora
- found in coastal waters (shellfish)
- many strains with antigenically different O Ag
- mode of transmission - contaminated water or food
- sesntitive to stomach acid - need large innoculum
- virulence
- flagella
- type IV pili
- ToxR - complex toxin part of filamentous phage ΦCTX genome
- ADP ribosylates G protein --> activates AC --> ↑ cAMP --> ↑ secretion of Cl, ↓ absorption of Na --> diarrhea
- clinical picture - severe diarrhea and vomiting
- diagnosis - TCBS culture (agglutinins in blood, oxidase+, motile, no H2S production
- Treatment
- vaccines
- oral rehydration therapy
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Term
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Definition
- watery diarrhea in newborns and infants
- colonizes rapidly --> septicemia, dehydration
- major cause of pediatric diarrhea and death in underdeveloped nations
- diagnosis: PCR for virulence factors
- treatment: neomycin
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Term
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Definition
- persistant diarrhea in children and infants
- non-invasive, heat-labile toxin
- clumping - adheres to surfaces of specific cell types
- Diagnosis: tissue culture assays for aggregated adherence
- treatment: rehydration
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Term
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Definition
- watery diarrhea in adults and children
- adheres diffusely to surface of various cell types
- diagnosis: tissue culture assays for diffuse adherence
- treatment: rehydration
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Term
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Definition
- S. dysenteriae, S. flexneri, S. boydii, S. sonnei (different O Ag)
- cause bacillary dysentery
- gram-, oxidase-, lactose-, no H2S, non-motile rods
- cannot be distinguished readily from E. coli by DNA hybridization --> different virulence properties
- clinical picture
- 2-4 day incubation
- frequent passage of stools w/blood, mucus, pus
- fever, abdominal pain, tenesmus
- pathogenesis
- survive stomach acid
- enter epithelial cells
- lyse phagosome and multply in cytosol
- inflammation and necrosis
- virulence
- plasmid borne invasion proteins
- shiga toxin (S. dysenteriae)
- irreversibly inactivates host 60S ribosome
- targes villus cells in colon - ↓ Na absorption - ↑ fluid loss
- cytotoxic effects on mucosal epithelial cells
- diagnosis - stool culture
- treatment - oral rehydration, antibiotics if very severe
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Term
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Definition
- non febrile bloody diarrhea or hemorrhagic colitis
- rare serotype O157:H7
- found in undercooked beef, contaminated ground water
- pathogenesis
- colonizes colonic epithelium
- produces Shiga-like toxins
- toxins can enter blood→ hemolytic uremic syndrome (kidney failure)
- diagnosis
- growth on sorbitol MacConkey
- most E. coli are sorbitol+
- EHEC is sorbitol-
- immunoassay to detect Shiga toxin in stool
- therapy - rehydration (antibiotics may increase risk of HUS)
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Term
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Definition
- gram-, oxidase+, single flagellum, rods often in pairs
- found in contaminated water, undercooked poultry and eggs
- symptoms - similar to dysentery, usually no dehydration
- pathogenesis
- small innoculum
- produce heat labile Shiga-like toxin
- colonizes both small and large intestine
- Diagnosis
- isolated from rectal and stool specimens
- cultured at 42° on CampyBAP medium
- Treatment
- antibiotics
- rehydration
- vaccine under development
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Term
| Salmonella enterica enteritidis |
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Definition
- pili, long wavy flagella, produces H2S oxidase-
- clinical picture
- 6-24 hours after ingestion - diarrhea, nausea, vomiting, fever, abdominal pain
- usually self-limiting
- pathogenesis
- often ingested in undercooked meat, poultry, eggs
- penetrate epithelium, multiply in lymph follicles
- infection contained to GI tract
- Type III secretion system delivers proteins to gut that disrupt cell fxn, cause inflammation, and stimulate ↑ cAMP and fluid secretion
- no known exotoxins
- treatment - supportive rehydration
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Term
| Salmonella enterica typhi |
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Definition
- typhoid fever
- normal flora in chicken, cattle, reptiles, but never humans
- clinical picture - fever, rash, constipation/diarrhea, delerium, rose-colored spots on abdomen
- pathogenesis
- systemic infection - can lead to septicemia, kidney, liver, spleen, and bone marrow involvement
- can remain in gallbladder - carrier state
- in colon, can cause severe diarrhea, hemorrhage, perforation
- virulence
- capsular V Ag
- flagella (H Ag) - phase variation
- cell invasion machinery
- intra-macrophage survival mechanisms
- endotoxin (LPS) - systemic inflammatory response
- Type III secretion system
- Diagnosis
- IgM, IgG Ab available to various Ags
- specimens in blood, stool, urine, bone marrow
- Treatment
- vaccines
- variety of antibiotics
- cholycystectomy if carrier
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Term
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Definition
- Enteroinvasive E. coli
- Shigella - like illness
- treated with antibiotics
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Term
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Definition
- bloody diarrhea, gastroenteritis
- found in seafood produces enterotoxin
- treatment: rehydration
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Term
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Definition
- septicemia, wound infections, gastroenteritis
- found in raw/undercooked seafood
- associated w/liver disease (alcohol, viral hepatitis)
- treated with tetracycline, 3rd generation cephalosporins
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Term
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Definition
- causes Yersiniosis, pseudoappendicitis
- gram- rod found in animals
- grows in mesenteric lymph nodes
- makes ST-like toxin - inflammatory
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Term
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Definition
- antibiotic-induced diarrhea, pseudomembranous colitis
- occurs after antibiotic treatment due to destruction of normal flora and overgrown of gram+ rods
- diagnosis: detection of toxin in stool
- treatment: vancomycin
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Term
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Definition
- emetic and diarrheal forms
- two toxins → ↑ cAMP levels
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Term
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Definition
- general characteristics
- gram- curved rod
- polar tuft of 4 - 7 flagella
- grows in stomach (normal flora for some)
- causitive agent of chronic gastritis and peptic ulcers
- risk factor for gastric adenocarcinoma and non-Hodgkin's lymphoma of stomach
- virulence
- flagella - move through mucin layer
- urease - forms ammonia w/in bacteria --> helps buffer incoming H+ ions
- adhesins - recognize carbohydrate Ag on surface of epithelial cells
- cag pathogenicity island
- type IV secretion system
- cagA - cytotoxin
- VacA - vacuolating cytotoxin --> tissue death
- clinical picture
- acute gastritis
- sometimes diarrhea
- chronic inflammation of gastric mucosa
- diagnosis
- gastric biopsy
- isolate bacteria
- test urease+
- treatment - triple therapy
- amoxicillin
- clarythromycin or Flagyl
- Omeprazole (H+ pump inhibitor)
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