Diarrheagenic Escherichia coli: Prevalence and Pathotype Distribution in Children from Peruvian Rural Communities

Abstract

Diarrheagenic Escherichia coli (DEC) are common pathogens of childhood gastrointestinal infections worldwide. To date, research tracking DEC has mainly been completed in urban areas. This study aims to determine the prevalence and pathotype distribution of DEC strains in children from rural Peruvian communities and to establish their association with malnutrition. In this prospective cohort, 93 children aged 6-13 months from rural communities of Urubamba (Andes) and Moyobamba (jungle) were followed for 6 months. Diarrheal and control stool samples were analyzed using multiplex real-time polymerase chain reaction to identify the presence of virulence genes of DEC strains. The overall isolation rate of DEC was 43.0% (352/820). Enteroaggregative E. coli (EAEC, 20.4%), enteropathogenic E. coli (EPEC, 14.2%), and diffusely aggregative E. coli (DAEC, 11.0%) were the most prevalent pathotypes. EAEC was more frequently found in Moyobamba samples (P < 0.01). EPEC was the only strain significantly more frequent in diarrheal than asymptomatic control samples (P < 0.01). DEC strains were more prevalent among younger children (aged 6-12 months, P < 0.05). A decline in height-for-age Z-score (HAZ) was observed in 75.7% of children overall. EAEC was more frequently isolated among children who had a greater HAZ decline (P < 0.05). In conclusion, DEC strains were frequently found in stool samples from children in rural communities of the highlands and jungle of Peru. In addition, children with a greater decline in their growth rate had higher EAEC isolation rates, highlighting the importance of this pathogen in child malnutrition.

Figure 1.

Distribution of diarrheagenic Escherichia coli (DEC) pathotypes in rural communities of the highlands and jungle. Urubamba N = 194 positive DEC samples; Moyobamba N = 227 positive DEC samples. * P < 0.05.

Figure 2.

Diarrheagenic Escherichia coli infections in children from both communities over time. Sample of 20 children randomly selected in each study site, among children with complete follow-up and at least one stool sample collected per month. ○ = negative sample, ♦ = positive for enteroaggregative E. coli, ▾ = positive for enteropathogenic E. coli, ▪ = positive for diffusely aggregative E. coli, ▴ = positive for enterotoxigenic E. coli.

Figure 3.

Frequency of diarrheagenic Escherichia coli pathotypes according to variation of height-for-age Z-score (HAZ) during follow up. Sample size: N = 22 children in ΔHAZ ≤ −1 group, N = 52 children in ΔHAZ > −1. Significant difference was found among the enteroaggregative Escherichia coli (EAEC) groups, ** P < 0.05.