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Flashcards in Quiz 3 GI Bugs Deck (26)
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Gram negative rod, found in Asia, Haiti, Africa. Large volume watery diarrhea, small bowel. Hypovolemic shock death. IV fluids and ORS. Azithro can shorten duration. Vibrio species are oxidase positive. Use TCBS agar, hardly anything grows on it but Vibrio. Vibrio like salt water and salt on plate helps it grow. Cholera does sucrose fermentation will turn colonies yellow.

Vibrio cholerae


-Gram positive rod, aerobic, spore-forming, enterotoxin causes diarrhea, cereulide toxin causes vomiting, goes away within 24 hours. Food poisoning, reheated fried rice.

Bacillus cereus


Food poisoning, gram positive cocci, has heat-stable toxin, goes away within 12 hours, cause from food prepared and left at room temp.  Causes vomiting.

Staph aureus


Gram negative rod. Food poisoning from contaminated shellfish. Doesn't ferment sucrose, stays green on TCBS agar. Oxidase positive.

Vibrio parahaemolyticus


Gram negative rod. Known as travelers diarrhea. Similar symptoms to Cholera but lower volume. Has watery diarrhea, cramps, malaise. Has heat labile toxin and heat stable toxins. ORS is huge, along with Azithro. Remember this is a small bowel, non-inflammatory. Also think galactosemia with regular E. Coli Sepsis.  Use Cefotaxime for normal E. Coli in newborns.

Enterotoxigenic E. Coli (ETEC)


SSCYEC - Salmonella, Shigella, Campylobacter, Yersinia, EHEC, C. Diff.

What is the acronym for inflammatory diarrhea pathogens?


Gram negative rod, facultative anaerobe, motile. Found in eggs, poultry, water, reptiles and amphibians. Fever, abdominal pain, watery diarrhea. Less bloody than Shigella. Can cause endocarditis, mycotic aneurysm, osteomyelitis. Manage with ORS. Salmonella typhi is similar but is a bloodstream invasion without diarrhea. Green and Black on HE agar. Non-lactose fermenting on MacConkey.  Produces H2S (black in tube).



Gram negative rod, facultative anaerobe, non-motile. Has a small inoculum, 10-100 organisms, doesn't need much to cause disease. Can invade colon cells. Causes dysentery: bloody diarrhea, fever, abdominal pain. Treat with ORS.  Green on HE agar. Non-lactose fermenting on MacConkey.



Gram negative rod, "gull" shaped rod. Microaerophilic, needs oxygen, but not too much. Found in retail poultry. Watery/blood diarrhea similar to salmonella symptoms. Kept at 42 C because that is body temp of birds and that is where they come from. Post-infectious problems are reactive arthritis, paralysis. Catalase and oxidase positive.



Gram negative rod, facultative anaerobe. Found in undercooked pork, similar symptoms to other inflammatory diarrheas. Has longer onset, and longer duration. Gives pseudoappendicitis and rheumatoid arthritis. CIN agar helps identify. Has bull's eye on CIN agar.

Yersinia enterocolitica


Gram negative rod. Found in hamburger meat. Produces shiga toxin. 3-4 days after ingestion symptoms occur, bloody diarrhea, no fever though. Abdominal pain. Hemolytic Uremia Syndrome happens in 10% of patients. Also called STEC, shiga-toxin producing E. Coli. STEC does not ferment sorbitol, while other E. Colis do.  Also, it is lactose-fermenting on MacConkey.

Enterohemorrhagic E. Coli (EHEC)


Gram positive rod. Anaerobic. Spore-forming and Toxic A and B. Is antibiotic associated, and fecal-oral. Diarrhea, fever, nausea, pseudomembranous colitis and toxic megacolon are key. Treated with metronizadole, fecal transplant, or colectomy. PCR may help detect asymptomatic carriers.

Clostridium Difficile


Gram negative rod. Motile, facultative anaerobe. Southeast Asia. Fecal-oral transmission, humans are the ONLY reservoir. Diarrhea not prominent. Fever but low heart rate which is opposite (pulse-temp disassoc). Causes rose spots. If left untreated, hallucinations, shock, perforations. Treat with azithro.

Salmonella typhi


Entamoeba histolytica is an amoeba, which is a protozoa. Can survive weeks outside the body. From ingestion of contaminated food/water, but the carriers are mostly asymptomatic. You get mild diarrhea to dysentery to colitis, but the main thing is a liver abscess. Treat with metronidazole, followed by a luminal agent. The cysts and trophozoites are passed in feces.

Entamoeba histolytica


Cryptosporidium parvum is a coccidian, which is also a protozoa. Involved in sporadic outbreaks in US. Is passed through fecal contaminated food/water, including recreational pools! Also found chronic in HIV patients and malnutritioned patients in third world countires. Gives you watery diarrhea, nausea, cramps. The immunocompromised have it prolonged and severe. Treat with ORS and Nitazoxanide if symptoms persist, but HIV patients are harder to treat.

Cryptosporidium parvum


Isosporiasis is another coccidian, more common in tropics. Fecal contaminated food/water. Gives you watery diarrhea and severe volume depletion. Immunocompromised get chronic diarrhea. Treat with TMP/SMX if HIV or with symptoms that don’t go away.



Cyclosporiasis is another coccidian, You get it from imported foods from Asia and South America. It’s cyst is resistant to chlorine. Same old GI symptoms. Treat with TMP/SMX.



Giardia lamblia is a flagellate, and its cysts can survive months in cold water. Found in daycare centers and with hikers. Contaminated food/water, and fecal-oral. You get diarrhea with excess fat in it (steatorrhea) and a fever is uncommon. Treat with metronidazole.

Giardia lamblia


Ascaris lumbricoides live 1-2 years. Over 1 billion people are infected. Ingestion from contaminated food/water. Most are asymptomatic, but you can get intestinal obstruction, Loeffler’s syndrome (pneumonitis), and biliary obstruction. Treat with Albendazole.

Ascaris lumbricoides


Trichuris trichiura is another nematode (roundworm). It lives in the colon, which is different from other roundworms. It is tricky! Found in tropical areas.  Ingestion of contaminated food/soil. It impairs growth and cognition in children. Treat with Mebendazole.

Trichurisis trichiura


Hookworms are also roundworms. The main one is Necator americanus, is from contaminated soil to skin, in Americas, causes diarrhea, nausea. With skin, you have hookworm-related cutaneous larva migrans. And when chronic you get anemia. Treat with albendazole.

Necator americanus (Hookworm)


Stongyloides stercoralis is another roundworm. Is endemic in tropical areas, from contaminated soil to skin, autoinfection. Has chronic mild GI symptoms, duodenitis, and the immunosuppressed (from steroids) get hyperinfection syndrome because strongyloides can carry gram negative bacteria into the bloodstream, CNS, lungs and cause sepsis. It is one of the few parasites that can complete it’s entire life cycle in host. This is often seen in someone born in Paraguay, first 10 years, then move to States and develop glomerulonephritis, so doctor gives them a whole bunch of steroids, causing immunosuppression. Strongyloides can produce offspring without going elsewhere, all in the human host. So you get dramatic increase of amount of worms. Patient presents with meningitis, you do a lumbar puncture, you grow E. Coli, Klebsiella, Proteus, which are Poop bugs and shouldn’t be in brain. If that were to occur, think Strongyloides. Not just meningitis, could happen in bloodstream, lungs, you get the picture. Just remember Strong-Steroids. Treat with Ivermectin.

Strongyloides stercoralis


Enterobius vermicularis is another roundworm, is most common helminth in US, passed from person to person, causes perianal itching.

Enterobius vermicularis


Wuchereria bancrofti and Brugia species. Happen through mosquito bites, acquired in childhood, most cases in Asia. Causes lymphedema, lower elephant leg, Treat with DEC. Onchocerciasis is river blindless, Dracunculiasis is guinea-worm (unfiltered water transmission), and Loa Loa is from deerfly bites, causes face swelling.

Non-GI roundworms:


Now for Cestodes (tapeworms). Taenia is the big one. Taenia sagniata is found in beef, Taenia solium is found in pork. Ingestion of these undercooked causes it, from scolex of parasite. Can go to brain (cystycercosis, this is ingestion of solium eggs shed by human). You get proglottids in anus, seizure if goes to brain. Treat with Praziquantel. -But also have Diphyllobothrium, which is in raw freshwater fish, and can cause megaloblastic anemia. -The Echinococcus species as well, ingestion of worm eggs, found in some animals, causes liver problems, and surgery is needed.

Cestodes (Tapeworms):


As for trematodes (flukes), the main one to know is Schistosoma species. They are released from snails, most prominent in Sub-Saharan Africa. They are from freshwater skin penetration, and at lower altitude. You get the swimmer’s itch and katayama fever which is high eosinophils, this is all for acute. For chronic, you get perioportal fibrosis and bladder fibrosis. Chonorchis is another trematode, it is considered the liver/biliary fluke, and from undercooked freshwater fish, and can give you cancer of biliary tract. The lung fluke is called Paragonimus, from undercooked seafood, causes lung fibrosis.

Trematodes (flukes):