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34 Cards in this Set
- Front
- Back
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How are E.coli classified?
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Serogroups and Serotypes
O antigen (LPS) - Serogroup O86 - normal O55 - rare (disease) H antigen (flagella) - Serotype |
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What are the 5 recognized virotypes?
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Enterotoxigenic (ETEC)
Enteroaggregative (EAggEC) Enteropathogenic (EPEC) Enterohemorrhagic (EHEC) - new Enteroinvasive (EIEC) |
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A patient comes in with cholera-like symptoms (diarrhea, vomiting), presenting like food poisoning, and they are a traveler. Which E. coli could it be? and which toxins types are associated?
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ETEC: Traveler's Diarrhea
Heat-labile (LT) - cholera-like toxins Heat-stable (ST) *fatal in infants |
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A child comes in with persistent diarrhea. Which E.coli is responsible? What toxin? Any special characteristics?
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EAggEC: not invasive/no changes to cells
ST-like toxin Special fimbriae (long and thin) |
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Microscopic examination of an intestinal mucosa reveals a patchy pattern with altered bound cells (lesions, and invasive) What E.coli do you suspect? Anything special about it?
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EPEC:
Has PI: LEE -Encodes: bundle forming pilus, -Encodes: Adhesin (intimin) Inserts own receptor (tir) - via Type III secretion system |
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Patient comes in with hemolytic uremic syndrome here in the US. Presents like Shigella dysentery. You think this is a new organism. What E.coli do you suspect?
Toxin? |
EHEC: O157:H7
Produces SLT (identical to Shiga toxin) -Bacteriophage encoded -Hypermutable -Intrinsic acid resistance is great |
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How do you confirm a diagnosis of E.coli O157:H7?
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White on MacConkey's sorbitol agar
Rapid test - MUG hydrolysis (-) |
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How are you going to treat EHEC?
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-Oral rehydration
-Antibiotics DO NOT effect it -DO NOT use antimobility agents, they will grow in numbers |
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What are complications of hemolytic uremic syndrome (HUS)?
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Acute renal failure (poor prognosis)
SLT, Type 1 toxin |
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What is the transmission of E.coli O157:H7?
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Beef and raw milk
Apple cider (downer apples) Person - person (low dose) |
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Whats the name of the E.coli strain that emerged in 2011?
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O104:H4
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What's the problem with packaged organic foods?
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Nitrogen packaging encourages bad bacteria growth
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How do we prevent O157:H7?
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Control corn fed cows/contaminated water
Proper hand washing Balanced diet |
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Your patient presents with what appears to be Shigella, however there is no Shiage toxin or HUS development. Microscopically the cells are nonmotile and are late or non-lactose fermenters. What type of E.coli is it?
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EIEC
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Patient is a bird collector. Microscopic sample is a G-, curved rod, motile, microaerophilic, grows at 42C.
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Campylobacter jejuni
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Patient presents prodrome with fever, headache, malaise, and myalgia. 1-2days later he gets diarrhea (loose stool, frank dysentery, enteritis) and has RLQ pain with inflamed mesenteric lymph nodes. What organism is it? How is it treated?
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Campylobacter jejuni
Self-limiting (improvement after several days) |
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What are Campylobacter jejuni's virulence factors?
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Invasion factor:
-carbohydrates on cell surface -pathogen-directed phagocytosis Heat Labile enterotoxin (like ETEC LT) Cytolethal distending toxins (CDTs) -destroys host cell DNA, not proteins (stuck in G2) -inhibits immune response |
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How is Campylobacter jejuni transmitted?
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Poultry products frequently contaminated (undercooked chicken)
Contaminated water Person-person (rare) |
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What are some characteristics of Campylobacter jejuni?
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Peaks in summer
Low dose Young Adults-highly infected |
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What are some complications of Campylobacter jejuni?
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Reiter's: HLA-B27 individuals
Guillain-Barre: LPS resembles human ganglioside (Gm1); Antibodies build up. |
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How do you diagnose Campylobacter jejuni?
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Fever, prodrome
Stool sample (motile curved rods/sea gull shaped Culture at 42C, microaerophilic conditions, enriched CO2 - selective Campy-BAP; Catalase (+) Oxidase (-) Latex agglutination (Campyslide) |
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How do you treat Campylobacter jejuni?
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Erythromycin
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You have a G(-), coccobacillus, motile, lactose nonfermenter, Facultative pathogen. Its optimal growth range is 22-29C. What organism is it?
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Yersinia enterocolitica
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How does Yersinia enterocolitica clinically manifest?
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Incubation 4-7d
Fever, abd pain, vomiting, diarrhea -Enterocolitis in children <5yo. -Ileitis in older children/adolescents -Transfusion reactions-grows and produce enterotoxin under refrigeration. |
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What are Yops?
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Plasmid encoded
Named for outer membrane proteins Inhibit phagocytosis, macrophage respiratory burst Cause contact-dependent cytotoxic activity that depolymerizes actin microfilaments of cells Synthesized at 37C/Low Ca2+ |
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Treatment for Yersinia enterocolitica?
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Supportive, maintain fluid, electrolyte balance
Aminoglycosides |
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How do you diagnose Yersinia enterocolitica?
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Culture medium with cold temp
Small lactose fermentation negative (white) MacConkey's lactose agar. |
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Epidemiology of Yersinia enterocolitica ?
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Ubiquitous, loves pigs
Outbreak in daycares Winter months fecal-oral (pork) Low dose Person-Person |
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Patient has chronic gastritis and peptic ulceration. G(-), curved rods, highly motile, Geimsa stain, urease production. You think what organism?
Detect with what test? |
Helicobacter pylori - many strains
Urease is its virulence factor CLO test (campylobacter-like organism) |
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What are Helicobacter pylori's virulence factors?
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Urease (and HspB)
- make CO2/NH4+ - Raise pH (Ammonia) Acid-inhibitory protein Adhesion proteins - stabilizes mucosal shedding - changes inflammatory response cag pathogenicity island - preturbs host signaling |
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What is the Epidemiology of Helicobacter pylori?
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Obscure source (human reservoir)
Large inoculum = gastritis Smoking is a risk factor |
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Consequences of Helicobacter pylori?
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gastric cancer
inflammation |
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How do you diagnose Helicobacter pylori?
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Biopsy/culture: 7d, blood-medium, high humidity, microaerophilic environment
CLO test - Urease detection Serologic - H. pylori antibodies |
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how do you treat Helicobacter pylori?
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No optimal therapy
Combo antibiotics (tetracycline) plus bismuth-containing drugs |
