Shiga toxin (Stx)-producing Escherichia coli (STEC) from patients with hemolytic-uremic syndrome (HUS), patients with diarrhea without HUS, or asymptomatic subjects were genotyped to assess associations between stx2 variants and clinical manifestations of infection. Neither stx2d nor stx2e was found in 268 STEC isolates from patients with HUS. Of 262 STEC isolates from patients with diarrhea, stx(2d) was found in 41 (15.6%; P<.000001), and stx2e was found in 12 (4.6%; P=.0004). The stx2c genotype frequency was similar among isolates from patients with HUS (3.7%) and diarrhea (5.0%). The frequencies of stx2c, stx2d, and stx2e among 96 STEC isolates from asymptomatic subjects were comparable to those among isolates from patients with diarrhea. None of the 626 STEC isolates contained stx2f. All stx2d-positive or stx2e-positive STEC isolates were eae negative and originated from subjects older than those with STEC isolates with stx2c. stx2c-positive STEC isolates can cause HUS, but the presence of stx2d or stx2e may predict a milder disease with a minimal risk of HUS.
In developed countries, acute gastroenteritis (AGE) is a major source of morbidity. However, only a few studies have estimated its incidence and the associated medical burden. This population-based study determined the incidence of community-acquired AGE patients seeking medical care and the relative role of various pathogens. Stool samples from patients with AGE presenting to a general practitioner (GP), pediatrician, or specialist in internal medicine for that reason were screened for various bacterial and viral enteropathogens. A control group was established as well.
The authors conducted a matched case-control study in Germany to identify risk factors for sporadic illness associated with Shiga toxin-producing Escherichia coli (STEC) infection, regardless of serogroup. From April 2001 through March 2003, cases were prospectively enrolled through a laboratory-based sentinel surveillance system located in 14 of the 16 German federal states. One control was identified per case, matched by age and region. Conditional logistic regression was used in the analysis, which was conducted separately for three age groups (<3 years, 3-9 years, and > or =10 years). The median age of the 202 enrolled cases was 2.5 years (range, 3 months-89 years). Hemolytic uremic syndrome developed in five patients. Non-O157 strains accounted for 85% of the isolated STEC. In children under 3 years of age, having touched a ruminant had the highest odds of disease, and raw milk was the only food identified as a risk factor. In contrast, in persons aged 10 years or older, only food items (i.e., lamb meat, raw spreadable sausages) were significantly associated with illness. In this study, risk factors were age-specific. Direct transmission through food played a lesser role in children under 3 years of age, the population at greatest risk of both acquiring STEC infection and developing hemolytic uremic syndrome.
Escherichia coli O157:H7 does not ferment sorbitol, a factor used to differentiate it from other E. coli. From December 1995 to March 1996, 28 children with hemolytic uremic syndrome in Bavaria, Germany, were identified; many had a sorbitol-fermenting (sf) E. coli O157:H- cultured. A case-control study showed a dose-response relationship between sausage consumption and illness. A second case-control study showed a relationship between mortadella and teewurst consumption and illness, particularly during December (mortadella odds ratio [OR], 10.5, P=.004; teewurst OR, 6.2, P=.02). Twelve sf O157:H- were characterized to determine clonality and virulence traits. The strains possessed the Stx2, eae, and EHEC-hlyA genes but were nonhemolytic on blood agar plates. The O157:H- isolates belonged to phage type 88 and had identical pulsed-field gel electrophoresis patterns. This outbreak was caused by sf E. coli O157:H-, which is not detectable by culture on sorbitol MacConkey's agar. Consumption of two sausages, including a raw beef-containing sausage, was statistically related to illness.
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