Objective: To describe pathogens identified through routine clinical practice and factors associated with identifying Shiga toxin-producing Escherichia coli (STEC) infection in patients with postdiarrheal hemolytic uremic syndrome (DHUS).
Design: Population-based active surveillance.
Setting: Hospitals in the FoodNet surveillance areas from 2000 through 2010.
Participants: Children younger than 18 years with DHUS.
Main exposures: Testing for STEC and demographic and clinical characteristics.
Main outcome measures: Percentage of patients with evidence of infection with likely HUS-causing agents and associations between exposures and evidence of STEC infection.
Results: Of 617 patients, 436 (70.7%) had evidence of infection with likely HUS-causing agents: STEC O157 (401 patients), non-O157 STEC (21 patients), O157 and non-O157 STEC (1 patient), Streptococcus pneumoniae (11 patients), and other pathogens (2 patients). Among patients without microbiological evidence of STEC, 76.9% of those tested had serologic evidence of STEC infection. Children more likely to have evidence of STEC infections included those patients tested for STEC less than 4 days after diarrhea onset, 12 months or older (71.6% vs 27.8% if <12 months of age), with infections as part of an outbreak (94.3% vs 67.3%), with bloody diarrhea (77.2% vs 40.4%), with onset during June through September (76.9% vs 60.1%), with a leukocyte count greater than 18 000/μL (to convert to ×10(9)/L, multiply by 0.001) (75.7% vs 65.3%), or with only moderate anemia (hemoglobin 7.0 g/dL [to convert to grams per liter, multiply by 10] or hematocrit greater than 20% [to convert to a proportion of 1, multiply by 0.01]) (75.1% vs 66.3%). However, many of these associations were weaker among children with thorough STEC testing.
Conclusions: Early stool collection for E coli O157 culture and Shiga toxin testing of all children with possible bacterial enteric infection will increase detection of STEC strains causing HUS. In the absence of microbiological evidence of STEC, serologic testing should be performed.