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26 Cards in this Set
- Front
- Back
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EHEC
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eating pink hamburgers
does not produce LT or ST but DOES make Shigella-like toxin Attaches and effaces Large intestine pediatric diarrhea - copious bloody discharge HUS - thrombycytopenia, kidney failure "pedestal formation" on EM AB treatment is contraversial |
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Shigella Etiology and Pathogenesis
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similar to E coli
Non lactose fermenting gram negative rods DO NOT produce H2S DO NOT produce gas most effective amoung enteric pathogens. S. Sonnei (group D) is most common in US. S. dysenteriae (group A - shiga toxin similar to E coli) most common in 3rd world. target M cells in Peyer's patches. No bacteremia, Shiga toxin cleaves 28S rRNA in 80S subunit |
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Shigella Transmission and Diagnosis
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diagnose with Methyl blue and presence of PMNs (does not rule out other invasive pathogens)
transmit human to human the 4 f's of fecal-oral route food born more common than water borne usually children under 10 |
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Shigella Treatment and Prevention
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treat with fluid and electrolyte replacement
severe cases treat with Cipro (FQ) empahsize personal hygiene to prevent |
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Symptoms of typhoid (salmonella)
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necrosis of ileum
fibrinous exudate abdominal maculopapular lesion fever diarrhea, hemorrhage, cholecystitis, kidney damages |
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Typhoid (salmonella) septicemia
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underlying chronic disease - sickle cell anemia or cancer
bacteremia results in osteomyelitis, pneumonia, meningitis |
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Typhoid (salmonella) Enterocolitis
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invasion of subepithelial tissue of small and large intestines
PMN's respond to limit the infection in the gut and surrounding lymph nodes gastric acid is an important host defense |
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Salmonella multiplication
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salmonella multiplies in lamina propria with uncertain mechanisms
salmonella not killed in macrophages |
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Treatment of Salmonella
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symotomatic relief
select AB's based on resistance target poultry industry for prevention vaccine is 50% effective |
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Yersiniae
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gram negative rods
anearobes, zoonotic do NOT ferment lactose oxidase negative plasmids with all virulence genes Y. Pestis - bubonic and pneumonic plagues - protein capsule |
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Yersinae enterocolitis
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caused by entercolitica and psuedotuberculosis
- identical symptoms as salmonella and shigella - cause mesenteric adenitis - mimics appendicitis enterocolitica more common in colder parts of US |
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Treatment for Yersina
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psuedotuberculosis - abscesses - treat with ampicillin and tetracycline
entercolitica - chronic abscesses - treat with ampicillin and chloramphenicol, polymyxin prevent by water treatment |
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Clostridium difficile
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gram positive - spore forming
strict anaerobe - makes toxins linked to exposure with C. difficile - psuedomembranous lesions |
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Antibiotic associated diarrhea
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classically associated with the use of clindamycin
now associated with many other broad spectrum AB's enterotoxin - chemotaxis cytotoxin B - depolarization of actin |
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Campylobacter jejuni
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gram negative, slender, comma shaped
cannot oxidize or ferment carbs motile, microaerophilic catalase and oxidase positive urease negative |
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campylobacter enteritis
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similar to salmonella and shigella
inflammatory enteritis, throughout whole mucosa villi atrophy necrotic debris thickening of basement membrane |
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Campylobacter diseases
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gastroenteritis - competent immune system
diarrhea and septicemia - in immunocomprimised host -- associated with Guillan-Barre syndrome -- |
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Treatment of Campylobacter
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gastroenteritis is self limiting
erythromycin is AB of choice followed by tetracycline and FQ systemic infections treated with aminoglycosides |
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Helicobacter pylori
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chronic infection of about 50% of worlds polulation
colonizes gastric mucosa class 1 carcinogen very common in patients who die from gastric cancer |
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H. pylori Diseases
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chronic active gastritis
peptic ulcer disease MALT lymphoma possible stomach adenocarcinoma |
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H pylori structrue
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gram negative
curved shaped with a bundle of flagella at one end has Oxidase, Urease, catalase, and phosphatase 2 big virulence factors... Urease and Flagella |
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Pathogenesis of H pylori
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pH must be above 4
stays in mucus layer and produces urease to buffer acid produces vacuoloating cytotoxin - VacA produces CagA - causes more damage when expressed |
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H pylori chronic gastritis
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lymphoplasmacytic infiltrate in the lamina propria of fundus and other regions
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H pylori and Adenocarcinoma
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most common form of gastric cancer
inflammation and toxin release causes mutations which may lead to adenocarcinoma |
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H pylori and MALT lymphoma
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lymphoid tissue regresses after H pylori is eradicated
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treatment of H pylori
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pepto bismol inhibits growth
first line: treat with proton pump inhibitor and 2 AB's (clarithromycin and amoxicillin) -- 1 week, twice a day -- second line: proton pump inhibitor bismuth susalicylate and tetracycline and metrondazone -- twice a day for 2 weeks -- |
