Abstract
BackgroundDiarrheagenic Escherichia coli (DEC) are among the leading pathogens associated with endemic diarrhea in low income countries. Yet, few epidemiological studies have focused the contribution of enterohemorrhagic E. coli (EHEC), enteroinvasive E. coli (EIEC) and diffusely adherent E. coli (DAEC).MethodsWe assessed the contribution of EHEC, EIEC and DAEC isolated from stool samples from a case-control study conducted in children aged < 5 years in Southern Mozambique between December 2007 and November 2012. The isolates were screened by conventional PCR targeting stx1 and stx2 (EHEC), ial and ipaH (EIEC), and daaE (DAEC) genes.ResultsWe analyzed 297 samples from cases with less-severe diarrhea (LSD) matched to 297 controls, and 89 samples from cases with moderate-to-severe diarrhea (MSD) matched to 222 controls, collected between November 3, 2011 and November 2, 2012. DEC were more common among LSD cases (2.7%, [8/297] of cases vs. 1.3% [4/297] of controls; p = 0.243]) than in MSD cases (0%, [0/89] of cases vs. 0.4%, [1/222] of controls; p = 1.000). Detailed analysis revealed low frequency of EHEC, DAEC or EIEC and no association with diarrhea in all age strata. Although the low frequency, EIEC was predominant in LSD cases aged 24–59 months (4.1% for cases vs. 0% for controls), followed by DAEC in similar frequency for cases and controls in infants (1.9%) and lastly EHEC from one control. Analysis of a subset of samples from previous period (December 10, 2007 and October 31, 2011) showed high frequency of DEC in controls compared to MSD cases (16.2%, [25/154] vs. 11.9%, [14/118], p = 0.383, respectively). Among these, DAEC predominated, being detected in 7.7% of cases vs. 17.6% of controls aged 24–59 months, followed by EIEC in 7.7% of cases vs. 5.9% of controls for the same age category, although no association was observed. EHEC was detected in one sample from cases and two from controls.ConclusionsOur data suggests that although EHEC, DAEC and EIEC are less frequent in endemic diarrhea in rural Mozambique, attention should be given to their transmission dynamics (e.g. the role on sporadic or epidemic diarrhea) considering that the role of asymptomatic individuals as source of dissemination remains unknown.
Highlights
Diarrheagenic Escherichia coli (DEC) are among the leading pathogens associated with endemic diarrhea in low income countries
As part of the Global Enteric Multicenter Study (GEMS) we have previously demonstrated that enterotoxigenic E. coli (ETEC), producing stable toxin (ST-ETEC) was the only E. coli pathotype associated to moderate-to-severe diarrhea (MSD) [16] and less-severe diarrhea (LSD) [17] in toddlers (12–23 months) in Mozambique
We analyzed 297 stools samples from cases with LSD matched to 297 controls, and 89 stool samples from cases with MSD matched to 222 controls, collected between November 3, 2011 and November 2, 2012
Summary
Diarrheagenic Escherichia coli (DEC) are among the leading pathogens associated with endemic diarrhea in low income countries. Few epidemiological studies have focused the contribution of enterohemorrhagic E. coli (EHEC), enteroinvasive E. coli (EIEC) and diffusely adherent E. coli (DAEC). DEC have been traditionally classified in six groups based on their clinical, epidemiological and virulence traits: enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enteroinvasive E. coli (EIEC), enteroaggregative E. coli (EAEC), diffusely adherent E. coli (DAEC) and enterohemorrhagic E. coli (EHEC) [6,7,8]. Studies reporting the occurrence of DEC in Mozambique remain scarce, and often focus on molecular screening of the three most common pathotypes (EAEC, ETEC and EPEC) [5, 11, 14,15,16,17] rather than all DEC. In this study, we investigated the contribution of those pathotypes on diarrheal etiology in children aged < 5 years enrolled in the GEMS in Manhiça, southern Mozambique between December 10, 2007 and November 2, 2012
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