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35 Cards in this Set
- Front
- Back
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Vibrio cholerae
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-Gram negative rod, looks like comma ("c" for cholera = comma), flagellum
-MECH -enterotoxin alters intestinal permeability -> fluid loss in small intestine -SOURCE -fecal contamination of standing water -SX -can be asx - severely ill *RICE WATER STOOL* -sx due to fluid, electrolyte loss -TX -restore fluid, electrolytes -tetracycline, ciprofloxacin |
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Vibrio parahaemolyticus
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-Gram negative rod, looks like comma, flagellum
-MECH -enterotoxin alters intestinal permeability -> fluid loss in small intestine -hemolysins -SOURCE -*saltwater, seafood* -SX -explosive diarrhea (not as profuse as cholera) -may have bloody dysentery -fevers in 25-50% -TX -restore fluid, electrolytes -tetracycline, ciprofloxacin |
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Aeromonas
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-Gram negative rod
-MECH -enterotoxins, hemolysins, cytotoxins -SOURCE -untreated water (well or spring) -SX -mild-severe diarrhea -may have blood, mucus in stool -TX -TMP-SMX, fluoroquinolones, tetracycline, 3rd-cephalosporins -B-lactam resistant |
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Escherichia coli
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-Gram negative rod
-MECH -toxin -adherence to epithelium of small, large intestine -> dissoluation of glycocalyx, flattening/destruction of microvilli -SOURCE -people, animals -SX -watery diarrhea -TX -restore fluid, electrolytes -tetracycline, ciprofloxacin Enteroaggregative -some children have bloody diarrhea -chronic diarrhea in HIV/AIDS -fluoroquinolones reduce duration Enterotoxigenic -upper GI distress followed by watery diarrhea -toxins similar to those from V. cholera -contaminated food, beverages -restore fluids, electrolytes -sensitive to most antibiotics Enterohemorragic -bloody diarrhea -hemolytic-uremic syndrome -thrombotic thrombocytopenia purpura -adherence mechanism -*hamburger meat, uncooked meat, apple cider, lettuce, alfalfa, unpasteurized milk* -supportive care (risk may increase with antibiotics) Enteroinvasive -watery diarrhea, sometimes blood, mucus -shiga-like toxin, enterotoxin -invades epithelial cells -*cheese* -restore fluids, electrolyes |
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Shigella
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-Gram negative
-MECH: -colonic epithelium invaded -generally don't invade blood -SOURCE: -fecal-oral -SX: -*DYSENTERY*, abdominal cramping, rectal burning, fever -TX: -restore fluids, electrolytes -quinolones, nalidixic acid in severe cases |
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Salmonella
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-Gram negative bacilli
-MECH: -ileal epithelium invaded, colonic to lesser extent -moves into lymphatics, blood, other organs -can survive within macrophages -SOURCE: -*5 F's: flies, food, fingers, feces, fomites* -SX: -gastroenteritis, bacteremia, localized infection, typhoid fever (fever, tender hepatomegaly) -TX: -flyoroqhinolone for immunocompromised |
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Campylobacter
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-Gram negative comma-shaped, flagella
-MECH: -small intestine epithelium invaded, can invade blood -SOURCE: -animals and their food products -SX: -*DYSENTERY*, fever, may have blood in stool -*may trigger Guillain-Barre* -TX: -erythromycin, fluoroquinolones |
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Yersinia enterocolitica
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-Gram negative rod, urease positive
-MECH: -bowel epithelium invaded -SOURCE: -streams, lakes, animals -contaminated milk -SX: -fever, abdominal cramps, diarrhea; *can mimic APPENDICITIS* -small abscesses in liver -TX: -TMP-SMX, fluoroquinolones, tetracycline in severe cases |
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Rotavirus
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-double-stranded RNA
-MECH: -enterotoxin -activates enteric nervous system -> intestinal secretion, diarrhea -selevtively infects, destroys mature enterocytes in small intestine -> repopulated with immature secretory cells -SOURCE: -fecal-oral -SX: -watery diarrhea -TX: -restore fluids, electrolytes |
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Calciviruses (Norovirus)
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-MECH: -attacks upper small intestine -> patchy mucosal lesions
-SOURCE: -fecal-oral -*cruise ships*, schools, hospitals, nursing homes -SX: -diarrhea, nausea/vomiting, abdominal cramps, muscle aches -TX: -treat symptoms |
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Enteric adenovirus
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-MECH: -unknown
-SOURCE: -person-to-person -SX: -*day-care children*, *AIDS patients* -TX: -supportive |
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Staphylococcus aureus
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-Gram positive coccus, clusters, catalase positive
-MECH: -enterotoxins -SOURCE: -*foods with high salt or sugar* -usually slustered within family -SX: -profuse nausea/vomiting, abdominal cramps, diarrhea -TX: |
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Clostridium perfringens
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-Gram positive, spore-forming
-MECH: -cytotoxin works in ileum -SOURCE: -*POULTRY*, other meat -SX: -watery diarrhea, abdominal pain, vomiting (8-24 hrs after eating) -TX: |
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Clostridium botulinum
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-Gram positive rod
-MECH: -neurotoxins -SOURCE: -pre-formed toxin in *improperly preserved canned food* -infants: *honey* -SX: -lethargy, poor feeding (infants), constipation, decreased muscle tone -TX: |
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Bacillus cereus
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-Gram positive rod, spore-forming
-MECH: -enterotoxin similar to cholera -SOURCE: -*contaminated rice* -SX: -diarrhea, abdominal cramps, vomiting -TX: |
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Listeria
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-Gram positive bacilli, highly motile
-MECH: -SOURCE: -*soft cheeses, cole slaw, shrimp, pork, raw vegetables* -SX: -diarrhea, cramping precede fever, bacteremia -listerosis: bactermia can seed meninges, heart valves -can have neurologic sequelae -TX: |
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Clostridum difficile
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-Gram positive rod, spore-forming
-MECH: -alteration of normal flora by antibiotics allows colonization -toxins A, B -> intestinal secretion -SOURCE: -fecal-oral -*hospitals, nursing home, elderly* -SX: -fever, diarrhea, leukocytosis, abdominal pain, cramping -can progress to toxic megacolon, colonic perforation, death -TX: -stop precipitating antibiotics -metronidazole, vancomycin, probiotics |
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Giardia lamblia
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-extracellular flagellated intestinal protozoan
-MECH: -attach to brush border or duodenum, jejunum -SOURCE: -cysts in contaminated water, food, fecal-oral -SX: -asx-severe diarrhea, malabsorption -TX: -metronidazole |
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Entamoeba histolytica
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-extracellular intestinal protozoan (trophozoites)
-MECH: -adhere to colonic epitheilal cells, invade -SOURCE: -cysts in contaminated water, food, fecal-oral -SX: -*asx, dysentery, liver abscess, fever, chills, pleuritic chest pain referred to right shoulder* -*direct extension to lungs (empyema, abscesses, hepatobronchial fistulae), pericarditis* -TX: -depends on location -abscess - metronidazole, surgical drain -luminal- paromycin, diloxanide furoate, iodoquinol |
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Brucella
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-hepatic granulomas
-*pts. who slaughter pigs, cattle, goats, sheep* |
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Neisseria gonorrhea
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-perihepatitis - direct spread from pelvis to liver
-Fitz-Hugh-Curtis syndrome - sudden sharp RUQ pain in young women with pelvic gonorrhea |
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Treponema pallidum = syphilis
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-liver involvement with congential syphilis, secondary syphilis, late syphilis (not primary)
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Bartonella bacilliformis
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-endemic to Colombia, Ecuador, Peru
-fever, jaundice, hemolytic anemia, hepatosplenomegaly, lymphadenopathy -high mortality without tx -tx - chloramphenicol, tetracycline |
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Schistosoma
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-helminthe
-MECH - eggs in fresh water become miracidia -> infect snails, become cercaria -> released in water, penetrate skin -> lay eggs in intestine - severe granulomatous reaction in intestine, liver -SOURCE - *contaminated fresh water snails* -SX - redness at skin penetration, headache, fever, chills, anorexia, abdominal pain (2-4 weeks after exposure) - hepatomegaly, splenomegaly, lymphadenopathy, eosinophilia - portal hypertension, ascites, esophageal varices, hyperslenism -TX - praziquantel |
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Echinococcus granulosis
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-helminthe
-MECH - worm lives in dogs, wolves, coyotes, jackels, dingos -> sheep, goats, cattle, pigs serve as intermediate host for eggs, cysts -> eggs ingested in contaminated food, water, soil -> hatch in small intestine -> migrate through lymphatics to form cysts (mostly liver, can be any organ) -SOURCE - contaminated food, water, soil -SX - liver cysts usually asx for years as they grow (hydatid disease = liver cysts after ingesting eggs from dog feces) - abdominal pain, nausea/vomiting, hepatomegaly -rupture of cysts can cause urticaria, anayphylaxis, death -TX - surgical drainage - mebendazole, praziquantel |
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Hepatits A virus
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-single-stranded RNA, picornavirus
-MECH - -SOURCE - fecal-oral, rarely blood -SX - malaise, loss of appetite, fever, abdominal pain, diarrhea - jaundice, elevated ALT, PT, Anti-HAV IgM - liver failure rare, no chronic infection (lifelong immunity after infection -> Anti-HAV total antibody) -TX - rest for 1-3 months, hydration - prophylaxis: vaccination, intramuscular IG injection within 14 days of exposure |
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Hepatitis B virus
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-double-stranded circular DNA, hepadnavirus
-MECH - immune-mediated liver injury -SOURCE - heterosexual sex, vertical -SX - nausea, fatigue, loss of appetite - jaundice, elevated ALT, HBsAg (blood), HBeAg (blood, not diagnostic, indicates high/low replication), HBcAg (immunostain of liver bx) - Anti-HBs -> vaccination, prior infection/resolution - Anti-HBc IgM -> acute infection in last 6 months - Anti-HBc total antibody -> prior acute/chronic infection - Anti-HBe -> chronic infection, low replication, less liver disease -95% full immune response, 5% chronic infection, 1% liver failure - hepatocellular carcinoma after decades of chronic infection - vertical transmission -> 90% infected infants develop chronic -TX - alpha-interferon, oral anti-viral |
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Hepatits C virus
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-single-stranded RNA, flavivirus
-MECH - encodes one polyprotein -> cleaved by host/viral proteases to functional proteins - immune-mediated injury -SOURCE - transfusion, IV drug use, rarely sex or vertical -SX - acute rarely recognized - moderate ALT elevation, rare jaundice, 70% develop chronic - chronic - fatigue, normal-moderately elevated ALT, Anti-HCV, RIBA antibody test (confirmatory for suspected false positive), PCR (serum viral RNA, confirmatory), liver bx - cirrhosis -> hepatocellular carcinoma - porphyria cutanea tarda - sun-exposed blisters -TX - interferon + ribavirin |
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Hepatitis D virus
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-defective circular single-stranded RNA, hepatitis delta virus
-MECH - *requires HBV coinfection* for synthesis of envelope protein -SOURCE - sex, IV drugs, rarely vertical -SX - higher risk of progressing to cirrhosis than HBV alone - Anti-HDV IgG -TX - prevent/tx HBV |
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Hepatitis E virus
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-MECH - -SOURCE - fecal-oral -SX - *very similar to HAV* -> only causes acute - *20% mortality in pregnant women* -TX - |
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Epstein Barr virus
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-MECH - -SOURCE - -SX - fatigue, jaundice, elevated ALT - does not cause chronic hepatitis -TX - |
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Cytomegalovirus
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-MECH - usually immunocompromised -SOURCE - -SX - -TX - |
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Herpes
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-MECH - immunocompromised, preganancy (can be fatal) -SOURCE - -SX - syncytial inclusions surrounding "punched out" necrosis -TX - acyclovir |
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Tropheryma whippelii
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-rare
-MECH: -organism-laden macrophages accumulate in small intestinal lamina propria, lymph nodes -> impaired lymphatic transport -SOURCE: - -SX: -*GI malabsoprtion*, joints, lung, heart, liver, spleen, CNS -weight loss, diarrhea, malabsorption -*PAS (+) macrophage inclusions* -TX: -antibiotics |
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Helicobacter pylori
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-gram negative, urease positive, curved shaped
-MECH: - -SOURCE: - -SX: -duodenal, gastric ulcers -can lead to gastric cancer, lymphoma -TX: - |
