Enteritis Requiring Antibiotics


	Here's another set of questions. I didn't put Giardia in here even though one usually treats with antibiotics because I'm going to put it in with parasitology when I get there. QUESTIONS The family Enterobacteriaceae contains the group of gram negative rods we call _______________. They are (choose one): obligate anaerobes/obligate aerobes/facultative anaerobes. They are oxidase negative/positive. E. coli has a lipopolysaccharide toxin that activates kallikrein, Factor XII, and complement. The name for this toxin is _______________. Why doesn't it matter if E. coli is alive or dead in the septic patient's circulation? (In other words, why does the toxin work anyway?) Another E. coli toxin disrupts cAMP & cGMP regulation leading to massive fluid secretion, HCO3-, Na+ & K+ loss into the GI lumen. This toxin is called an _______________. The small piece of DNA which determines if an E. coli can produce this toxin, not to mention adhese to the ileal target cell) is called a _______________. The most important Salmonella species is: _______________. Salmonella infection can lead to one of three outcomes: 1) carrier state 2) enteric infection 3) invasive infection. Which should be treated with antibiotics? Salmonella diarrhea is commonly bloody while E. coli diarrhea commonly is not. Why? Campylobacter jejuni is a zoonotic organism. Is this organism rare in the environment, common, or ubiquitous? Who would be more resistent to infection: you or a 10 week old puppy? Campylobacter infection is confirmed by culture. What are the two main unique culture requirements of Campylobacter? Another way to diagnose Campylobacter is with a fecal Wright's stain. What is the characteristic appearance of Campylobacter? Penicillin Erythromycin Tribrissen Keflex An MD wants you to treat the family pet as a reservoir for the family's Campylobacter infection. The pet has diarrhea. Which antibiotic would you use of the above? Why might you not use any antibiotics? Describe the rationale behind breath hydrogen analysis for bacterial overgrowth of the small intestine. What percentage of dogs with EPI also have a significant bacterial overgrowth? In bacterial overgrowth will fasting serum folate by up or down classically? How about B12? Salmon poisoning is associated with a fluke called _______________; however, the actual agent of the disease is the rickettsia carried by the fluke. The name of this rickettsia is _______________. Complete blanks in the salmon poisoning life cycle: eggs passed in feces ---> eggs live 3+ months in environment of raccoon or skunk \| (in nature) \/ eggs hatch into miracidia which attack a snail called Oxytrema silicula \| \/ There they develop into _______________ break out of the snail & attack trout or salmon \| \/ Here, they develop into _______________ and remain up to 5 years waiting to be eaten by a definitive host. Prepatency period is 4-5 days. Clostridium perfringens true or false a) This organism causes both enteritis and enterotoxemia b) This organism usually produces a large bowel type diarrhea Which assay for clostridium enterotoxin is currently favored? ANSWERS These beloved bacteria are called "enterics". They are facultative anaerobes & oxidase negative. E. coli endotoxin is located in the cell wall & thus even if the circulating E. coli are dead, the endotoxin can still cause its effect. This other E coli toxin is an "enterotoxin." Plasmids are the little DNA pieces that determine if a bacterium can produce this toxin. The most important Salmonella species is Sal. Typhimurium There may be some controversy here but I was taught that antibiotics are bad for Sal carriers as they will prolong carrier state and cause resistence. Basically the same is true for enteric infections (treatment is by support). If the infection is invasive, though, then you have sepsis to tangle with and need antibiotics to save your patient's life. Sal diarrhea is bloody because in addition to the enterotoxin, Sal produces a cytotoxin which kills enterocytes. E. coli does not produce a cytotoxin. Campylobacter jejuni is thought to be ubiquitous. The puppy is probably more resistent than you. In CVT it says that 200-500 organisms will infect a person but 10 to the tenth are needed to infect small animal species. In small animals, Campy is really only a problem for pups & kits < 1 year old. Campy's unique culture requirements are 1) microaerophilia (it wants 5-10% oxygen only) 2) thermophilia (it wants 42-43 C) Campy is said to be "seagull" shaped. It is a Gram negative rod (obviously you wouldn't see it as gram negative with a Wright's stain but they say it shows up better with Wright's than Gram). Erythro is best choice though infection is self-limiting in a matter of days. Response to antibiotics is also fast (48-72 hours) if you use them. Some recommend using them simply to reduce shedding of zoonotic bacteria. Breath hydrogen: give animal a high carbohydrate meal & measure breath hydrogen in 2-4 hours. If elevated then you have bacterial overgrowth (the bacteria have produced lots of hydrogen). If the elevation occurs after 2-4 hours, you have a malabsorption. The CHO has made it to the colon and the colon bacteria have produced the hydrogen. My studies show 70% dogs with EPI have signif. overgrowth. Folate is up in overgrowth, B12 is down (by now, you better know this one). The fluke is Nanophyetes salmincola. The fluke is neorickettsia helminthoeca. Miracidia attack the snail and develop into cercaria. Cercaria attack the fish develop into metacercaria . Clostridium perfringens true or false a) This organism causes both enteritis and enterotoxemia This is true b) This organism usually produces a large bowel type diarrhea This is false There are two assays for the enterotoxin available. The reverse passive latex agglutination assay and the enzyme immunoassay. Neither is perfect but the latter has a much shorter incubation period (3 hours vs over night) plus also seems to have fewer false positives. (FYI we think enterotoxin is elaborated during the sporulation of the clostridial organism)