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38 Cards in this Set
- Front
- Back
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Is V. cholerae Gram-negative or positive? Is it oxidase-negative or positve?
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Gram-negative
Oxidase positive |
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Which V. cholerae serotypes are associated with epidemics and have the essential virulence factors?
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O1 and O139
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What does cholera generally cause?
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Profuse watery diarrhea (may be more than 1L/hr)
vomiting cramps electrolyte loss |
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What predisposes someone to a severe case of cholera?
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High dose exposure
Low gastric acidity Blood group O |
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What is the treatment for cholera?
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Tetracycline reduces duration of diarrhea
Oral rehydration therapy |
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What compounds are in the oral rehydration therapy for cholera?
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Glucose
Sodium chloride Potassium chloride Sodium bicarbonate |
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How many people who get cholera die from dehydration if they are not treated?
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60-80%
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Describe the pathogenesis of cholera?
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Uses type II secretion to get cholera toxin into enterocytes. Type II is much more efficient than Type III, so more diarrhea than ETEC. Cholera toxin is an AB toxin, and the A part activates adenylate cyclase (ADP-ribosylation activity) just like the heat-labile toxin from ETEC does. This blocks sodium and chloride absorption and increases chloride excretion
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Describe the importance of TCP for cholera.
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TCP - toxin co-regulated pilus
Type IV pilus whose expression is co-regulated with the cholera toxin. TCP is an essential colonization factor. |
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What are the two virulence factors for cholera?
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TCP - toxin co-regulated pilus
CT - cholera toxin |
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What does ToxR do?
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It regulates both the cholera toxin and the toxin coregulated pilus. Presence of ToxR turns on transcription of CT and TCP
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What are the main strains that cause epidemic cholera?
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O1 and O139
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Describe the vaccine for cholera?
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It is a live attenuated strain with the A subunit of the AB toxin missing
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Is Campylobacter Gram positive or negative?
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Negative
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Is Campylobacter aerobic or anaerobic?
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Microaerobic
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What is the reservoir for Campylobacter?
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Water and animals (chicken, cows, birds)
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What kind of clinical presentation does Campylobacter have?
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Inflammatory diarrhea much like Salmonella and Shigella
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What is the infectious dose for Campylobacter?
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500-800 cfu
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What is the pathogenesis of Campylobacter?
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Flagella required for invasion into cells
Releases cytolethal distending toxin, which creates breaks in double-stranded DNA and death Toxin is endocytosed by cells and then acts in the nucleus |
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What specific disease is associated with Campylobacter infection?
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Guillain-Barre syndrome
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How long after Campylobacter jejuni infection does Guillan-Barre syndrome start?
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1-3 weeks
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What are the two most common food-borne bacterial infections in the US?
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Campylobacter and Salmonella
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Is Salmonella gram positive or negative?
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Negative
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Is salmonella lactose fermenting or nonfermenting?
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Nonfermenting
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What diseases does Salmonella cause?
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Gastroenteritis - nausea, vomiting, diarrhea
Focal systemic infections - endocarditis, osteomyelitis Typhoid fever |
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What strain(s) of Salmonella cause(s) gastroenteritis?
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S. enterica
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What strain(s) of Salmonella cause(s) focal systemic infections?
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S. typhimurium and S. choleraesuis
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What strain(s) of Salmonella cause(s) typhoid fever?
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S. typhi and S. paratyphi
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What is the difference between typhoid and non-typhoid salmonella?
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Typhoid is a systemic syndrome with enteric fever - diarrhea not prominent
Non-typhoid is diarrhea |
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What is the infectious dose of salmonella?
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Millions
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What is the pathogenesis of salmonella?
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All salmonella are invase and get in the enterocytes. S. typhi then passes through the mucosa and enters the systemic circulation. On its way into the cell, salmonella causes drastic cytoskeletal alterations
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Which salmonella has a capsule? What type of capsule is it?
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S. typhi has a Vi capsule
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What kind of secretion system does salmonella use?
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Type III used for intracellular survival and immune evasion
Actually uses two different types: One injects proteins into enterocytes to allow salmonella to enter. The other causes vacuolar remodeling, which prevents lysosome fusing |
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What is the reservoir and incubation period for S. typhimurium?
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Animals
1-3 days |
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What is the reservoir and incubation period for S. typhi?
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Humans
A week |
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What is the cause of the fluid loss in S. typhimurium?
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Host inflammatory response, NOT chloride secretion
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How is salmonella transmitted?
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Food-borne - fecal contamination
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Is salmonella acid resistant or sensitive?
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Acid sensitive
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