Acute Diarrhea and E Coli 0157/H7 Morning Report Beth Duncan 11

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1 : Acute Diarrhea and E. Coli 0157/H7 Morning Report Beth Duncan 11/26/2008
2 : Diarrhea Acute - <14 days in duration Persistent – more than 14 d in duration Chronic – more than 30 d in duration When should you test and initiate therapy?
3 : Thielman and Guerrant NEJM, 350 (1): 38, Figure 1     January 1, 2004
4 :
5 : Historical Clues to Etiology of Diarrhea Fever: suggests an invasive bacteria (eg: Salmonella, Shigella, or Campylobacter), enteric viruses, or a cytotoxic organism (i.e. C dif or E hisolytica) Recent Abx use, other meds. Food History: Sxs within 6h suggest ingestion of a preformed toxin such as S. aureus or B. cereus Sxs that begin 8-16h suggest infn with C. perfringens Sxs >16h can result from viral or bacterial infn.
6 : Grossly Bloody Diarrhea Acute bloody diarrhea is uncommon, present in 3% of more than 30,000 stool cultures in a review from the US. A pathogen detected in 20% of all visibly bloody diarrhea E. coli 0157:H7 was present in 7.8% of all visibly bloody diarrhea. 39% of all pathogens found in bloody diarrhea. Less common bacterial causes of visibly bloody diarrhea are Shigella, Campylobacter, and Salmonella species.
7 : Fecal Leukocytes & Occult Blood as Indicators of Inflammatory Diarrhea Sensitivity & specificity ranges from 20-90% Tends to be 70-80% for these in studies from developed world. Differences in studies may be partially due to specimen processing & in operator experience.
8 : Utility of Stool Cultures Difficult to predict the presence of bacterial causes of acute diarrhea, because of low rate of positive stool cultures. It is reasonable to continue symptomatic treatment for several days before considering further evaluation in patients without severe illness, especially if occult blood & fecal leuks are absent. Stool culture not recommended for patients hospitalized >72h. (unlikely to get food-borne illness from the hospital?)
9 : Stool Cultures (cont) Stool cultures should be obtained on: Immunocompromised patients Patients with severe, inflammatory diarrhea (including bloody diarrhea) Patients with underlying inflammatory bowel disease Some employees (i.e. food handlers) need a negative stool culture to return to work.
10 : Ova and parasites Not cost effective for most patients with acute diarrhea When getting these send multiple specimens on consecutive days Patients who you should send O&P: Persistent diarrhea Persistent diarrhea following foreign travel. Persistent diarrhea with exposure to infants at daycare Diarrhea in MSM or a patient with AIDs Community waterborne outbreak Bloody diarrhea with few or no fecal leukocytes.
11 : Endoscopy Dist. IBD vs. infectious diarrhea Diagnosing C. dif & looking for pseudomembranes in patients who are severely ill. In immunocompromised patients at risk for opportunistic infections such as CMV. In patients in whom ischemic colitis is suspected
12 : Thielman and Guerrant NEJM, 350 (1): 38, Table 3     January 1, 2004 When and What : Considerations for antibiotics for acute diarrhea
13 : Pathogen Directed Therapy Thielman and Guerrant, NEJM, 350 (1): 38, Table 2     January 1, 2004
14 : Enterohemorrhagic E. Coli Originally identified in 1982 after 2 outbreaks of severe bloody diarrhea in 47 individuals occurred in Oregon & Michigan. Epidemiologic investigation found all these patients had eaten ground beef from the same fast food restaurant prior to illness. A new serotype of E. coli, 0157:H7, was isolated from the stool of all ill patients & hamburger meat, but not found in fecal flora of healthy individuals.
15 : Microbiology These organisms differ from other E. coli by production of Shiga toxin. Shiga toxins are produced by lysogenic phage. Shiga toxins are responsible for vascular damage (hemorrhagic colitis) & systemic effects of infection, such as HUS.
16 : “Shiga toxin-producing” E. coli, SHEC Also called verocytotoxic E. coli (VTEC) or enterohemorrhagic E. coli (EHEC); most common pathogen is E. coli 0157/H7 EHEC reflects the bloody diarrhea that is typically produced by this pathogen. EHEC differs from other pathogenic E. coli by the production of Shiga toxins. The main Shiga toxin producing EHEC in the US is O157:H7 EHEC causes illness in ~75,000 patients/year in the US. ~25-50% are in age >50. Non-0157 STEC are not as well understood & less likely to cause severe illness.
17 : Pathogenesis Infectious Dose: Shigella 10-100 organisms Campylobacter jejuni 10 (4) – 10 (6) organisms Salmonella 10 (5) – 10 (8) organisms Vibrio cholerae 10 (5) to 10 (8) organisms Enterotoxigenic E. coli 10 (8) organisms Yersinia enterocolitica 10(9) organisms EHEC (E. coli 0157: H7) 10-100 organisms
18 : Epidemiology Mechanisms of exposure in outbreaks: Retrospective study examined the frequency of the different mechanisms of transmission Foodborne 52% (41% beef, 21% produce) Person-to-person 14% Waterborne 9% Animal contact 3% Laboratory related 0.3% Unknown 21%
19 : Beef Contamination Most common reservoir for E. coli 0157:H7 is the GI tract of cattle E. coli 0157:H7 is excreted by up to 10% of healthy cattle Beef is contaminated when intestinal contents from an infected animal contact the meat during slaughter- ~1% of retail ground beef is culture positive for 0157. A small number of infected cattle can contaminate a large supply of ground beef because of the substantial mixing of meat from different cows in ground beef.
20 : Frequency of EHEC as a Cause of Bacterial Acute Diarrhea Campylobacter – 42% of all isolates Salmonella – 32% of all isolates Shigella – 19% of all isolates E. Coli O157:H7 – 7% of all isolates
21 : Crossroads Farm Petting Zoo E. coli Outbreak - North Carolina In late October 2004, the North Carolina Division of Public Health (NCDPH) received several reports of HUS (15 kids) among North Carolina residents who had attended the State Fair, which ran from October 14 to 24 in Raleigh, North Carolina.  NCDPH recognized the potential for a large outbreak and immediately alerted local health departments, asking them to increase surveillance for diarrheal illnesses and requested epidemiologic support from the Centers for Disease Control and Prevention (CDC).
22 :
23 : Clinical Manifestations Incubation period is 3-4 days Most common syndrome is hemorrhagic colitis, also abdominal pain & tenderness without fever, peripheral wbc >10,000/ul Hospitalization is required in 23-47% of symptomatic patients with acute diarrhea with median stay of 6-14 days.
24 : Hemolytic-uremic syndrome Most worrisome complication of EHEC infection- most frequently in kids age 5-10 Triad of ARF, microangiopathic hemolytic anemia, and thrombocytopenia. HUS complicates up to 9% of EHEC infections & usually begins 5-10 days after onset of diarrhea EHEC causes at least 70% of postdiarrheal HUS in the US.
25 : Diagnosis Rate of stool isolation is highest in the first 6 days after onset of diarrhea. Some labs screen all stools for E. coli O157:H7, others only on request. Since 95% of cultures positive for E. coli O157:H7 come from patients with visibly bloody stools it is reasonable to only screen bloody stools. Newer techniques being developed that focus on direct detection of Shiga toxins in stool, or DNA probes for detecting the toxin genes in fecal isolates.
26 : Treatment Supportive with monitoring for development of microangiopathic complications such as HUS. Antiperistaltic agents increase the risk of systemic complications Antibiotic therapy has no effect on the duration of acute diarrhea.- actually in vitro data suggests that certain antibiotics increase production/release of toxins by EHEC.
27 : Prevention of E. coli 0157/H7 WASH YOUR HANDS thoroughly after using the bathroom or changing diapers and before preparing or eating food. WASH YOUR HANDS after contact with animals or their environments (at farms, petting zoos, fairs, even your own backyard) COOK meats thoroughly. Ground beef and meat that has been needle-tenderized should be cooked to a temperature of at least 160°F/70°C. It’s best to use a thermometer, as color is not a very reliable indicator of “doneness.” AVOID raw milk, unpasteurized dairy products, and unpasteurized juices (like fresh apple cider). AVOID swallowing water when swimming or playing in lakes, ponds, streams, swimming pools, and backyard “kiddie” pools. PREVENT cross contamination in food preparation areas by thoroughly washing hands, counters, cutting boards, and utensils after they touch raw meat.
28 : References Rangel JM, et. al., “Epidemiology of Escherichia coli 0157:H7 outbreaks, United States, 1982-2002.” Emerg Infect Dis. 2005, 11:603. Thielman and Guerrant “Acute Infectious Diarrhea.” NEJM, 2004, 350 (1): 38 Up to Date 2008


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