Diarrhea etiology in a pediatric emergency department: a case control study.

BACKGROUND: The etiology of childhood diarrhea is frequently unknown. METHODS: We sought Aeromonas, Campylobacter, Escherichia coli O157:H7, Pleisiomonas shigelloides, Salmonella, Shigella, Vibrio, and Yersinia (by culture), adenoviruses, astroviruses, noroviruses, rotavirus, and Shiga toxin-producing E. coli (STEC; by enzyme immunoassay), Clostridium difficile (by cytotoxicity), parasites (by microscopy), and enteroaggregative E. coli (EAEC; by polymerase chain reaction [PCR] analysis) in the stools of 254 children with diarrhea presenting to a pediatric emergency facility. Age- and geographic-matched community controls without diarrhea (n = 452) were similarly studied, except bacterial cultures of the stool were limited only to cases. RESULTS: Twenty-nine (11.4%) case stools contained 13 Salmonella, 10 STEC (6 O157:H7 and 4 non-O157:H7 serotypes), 5 Campylobacter, and 2 Shigella. PCR-defined EAEC were present more often in case (3.2%) specimens than in control (0.9%) specimens (adjusted odds ratio [OR], 3.9; 95% confidence interval [CI], 1.1-13.7), and their adherence phenotypes were variable. Rotavirus, astrovirus, and adenovirus were more common among cases than controls, but both groups contained noroviruses and C. difficile at similar rates. PCR evidence of hypervirulent C. difficile was found in case and control stools; parasites were much more common in control specimens. CONCLUSIONS: EAEC are associated with childhood diarrhea in Seattle, but the optimal way to identify these agents warrants determination. Children without diarrhea harbor diarrheagenic pathogens, including hypervirulent C. difficile. Our data support the importance of taking into account host susceptibility, microbial density, and organism virulence traits in future case-control studies, not merely categorizing candidate pathogens as being present or absent.

Risk factors for the hemolytic uremic syndrome in children infected with Escherichia coli O157:H7: a multivariable analysis.

BACKGROUND: Escherichia coli O157:H7 is the leading cause of hemolytic uremic syndrome (HUS). Risk factors for development of this complication warrant identification. METHODS: We enrolled children infected with E. coli O157:H7 within 1 week of the onset of diarrhea in this prospective cohort study. The study was conducted in 5 states over 9.5 years . The primary and secondary outcomes were HUS (hematocrit <30% with smear evidence of hemolysis, platelet count <150 × 10(3)/µL, and serum creatinine concentration > upper limit of normal for age) and oligoanuric HUS. Univariate and multivariable and ordinal multinomial regression analyses were used to test associations between factors apparent during the first week of illness and outcomes. RESULTS: Of the 259 children analyzed, 36 (14%) developed HUS. Univariate analysis demonstrated that children who received antibiotics during the diarrhea phase more frequently developed HUS than those who did not (36% vs 12%; P = .001). The higher rate of HUS was observed across all antibiotic classes used. In multivariable analysis, a higher leukocyte count (adjusted odds ratios [aOR] 1.10; 95% CI, 1.03-1.19), vomiting (aOR 3.05; 95% CI, 1.23-7.56), and exposure to antibiotics (aOR 3.62; 95% CI, 1.23-10.6) during the first week of onset of illness were each independently associated with development of HUS. Multinomial ordinal logistic regression confirmed that initial leukocyte count and antibiotic use were independently associated with HUS and, additionally, these variables were each associated with the development of oligoanuric HUS. CONCLUSIONS: Antibiotic use during E. coli O157:H7 infections is associated with a higher rate of subsequent HUS and should be avoided.

Proinflammatory fecal mRNA and childhood bacterial enteric infections.

INTRODUCTION: Assessment of specific mRNAs in human samples is useful in characterizing disease. However, mRNA in human stool has been understudied. RESULTS: Compared to controls, infected stools showed increased transcripts of IL-1ß, IL-8 and calprotectin. mRNA and protein concentrations correlated for IL-8, but not for calprotectin. DISCUSSION: Stool mRNA quantification offers a potentially useful, noninvasive way to assess inflammation in the gastrointestinal tract, and may be more sensitive than EIA. METHODS: We purified fecal RNA from 46 children infected with Campylobacter jejuni, Escherichia coli O157:H7, Salmonella spp. or Shigella sonnei and 26 controls and compared the proportions of IL-1ß, IL-8, osteoprotegerin and calprotectin mRNA between groups using qRT-PCR. We determined the concentrations of calprotectin, IL-8 and osteoprotegerin by enzyme immunoassays in cognate specimens.

Lipopolysaccharide from enterohemorrhagic Escherichia coli binds to platelets through TLR4 and CD62 and is detected on circulating platelets in patients with hemolytic uremic syndrome.

This study presents evidence that human platelets bind lipopolysaccharide (LPS) from enterohemorrhagic Escherichia coli (EHEC) through a complex of toll-like receptor 4 (TLR4) and CD62, leading to their activation. TLR4 colocalized with CD62 on the platelet membrane, and the TLR4 specificity of LPS binding to platelets was confirmed using C57BL/10ScN mice lacking Tlr4. Only platelets from TLR4 wild-type mice bound O157LPS in vitro. After in vivo injection, O157LPS bound to platelets from wild-type mice, which had lower platelet counts than did mice lacking TLR4. Mouse experiments confirmed that O157LPS binding to TLR4 is the primary event leading to platelet activation, as shown by CD40L expression, and that CD62 further contributes to this process. Activation of human platelets by EHEC-LPS was demonstrated by expression of the activated GPIIb/IIIa receptor, CD40L, and fibrinogen binding. In perfusion experiments, platelet activation on endothelial cells was TLR4 and CD62 dependent. O157LPS was detected on platelets from 12 of 14 children with EHEC-associated hemolytic uremic syndrome (HUS) and on platelets from 2 children before the development of HUS but not on platelets of EHEC-infected children in whom HUS did not develop (n = 3). These data suggest that O157LPS on platelets might contribute to platelet consumption in HUS.