Genotypic and Phenotypic Characterization of Enterotoxigenic Escherichia coli Strains Isolated from Peruvian Children

Abstract

Enterotoxigenic Escherichia coli (ETEC) is a major cause of childhood diarrhea. The present study sought to determine the prevalence and distribution of toxin types, colonization factors (CFs), and antimicrobial susceptibility of ETEC strains isolated from Peruvian children. We analyzed ETEC strains isolated from Peruvian children between 2 and 24 months of age in a passive surveillance study. Five E. coli colonies per patient were studied by multiplex real-time PCR to identify ETEC virulence factors. ETEC-associated toxins were confirmed using a GM1-based enzyme-linked immunosorbent assay. Confirmed strains were tested for CFs by dot blot assay using 21 monoclonal antibodies. We analyzed 1,129 samples from children with diarrhea and 744 control children and found ETEC in 5.3% and 4.3%, respectively. ETEC was more frequently isolated from children >12 months of age than from children <12 months of age (P < 0.001). Fifty-two percent of ETEC isolates from children with diarrhea and 72% of isolates from controls were heat-labile enterotoxin (LT) positive and heat-stable enterotoxin (ST) negative; 25% and 19%, respectively, were LT negative and ST positive; and 23% and 9%, respectively, were LT positive and ST positive. CFs were identified in 64% of diarrheal samples and 37% of control samples (P < 0.05). The most common CFs were CS6 (14% and 7%, respectively), CS12 (12% and 4%, respectively), and CS1 (9% and 4%, respectively). ST-producing ETEC strains caused more severe diarrhea than non-ST-producing ETEC strains. The strains were most frequently resistant to ampicillin (71%) and co-trimoxazole (61%). ETEC was thus found to be more prevalent in older infants. LT was the most common toxin type; 64% of strains had an identified CF. These data are relevant in estimating the burden of disease due to ETEC and the potential coverage of children in Peru by investigational vaccines.

Diarrheagenic Escherichia coli pathotypes isolated from children with diarrhea in the Federal Capital Territory Abuja, Nigeria

“…We identified ETEC in all age groups except in the 37-48 months group, from which no ETEC strain was isolated. The highest ETEC prevalence in our results was observed among children 49-60 months of age, which is similar to the findings of Riveria et al and conforms with the commonly reported more frequently isolation of ETEC from children > 12 months of age than from children < 12 months of age [39]. This corroborates the fact that ETEC strains might be considerably important enteropathogens, especially in pediatric patients in the 0-5 years age group [40].…”

Molecular Characterization of Enterotoxigenic Escherichia coli Isolates Recovered from Children with Diarrhea during a 4-Year Period (2007 to 2010) in Bolivia

“…However, variations in toxin profiles were observed from year to year. Different studies in Latin America have shown differences in the predominant toxin type; for instance, LT/ST ETEC strains were found to be most prevalent in Peru (19), ST-only ETEC strains in Brazil (20) and LT ETEC strains in Argentina (23), in Nicaragua (21), and in a previous report from Bolivia (16). A similar trend has been observed in Bangladesh, where different toxin profiles have predominated over the years (24)(25)(26).…”

“…In Bolivia, a previous report showed that ETEC strains expressing LT CS17 constituted the most common pathotype isolated between 2002 to 2005, but those strains were from different clonal origins (31). In recent studies in Peru, CS6-and CS12-positive strains (19), and, in Brazil, CFA/I-and CS14-expressing ETEC strains (20) were the predominant pathotypes. Several review articles have indicated that a limited number of CFs, including CFA/I, CS1 to -6, and, more recently, CS7, CS14, and CS17, are repeatedly identified as the most common CFs for ETEC, suggesting a continuous circulation of similar strains among populations (2,6,32).…”

Real-Time PCR-Based Mismatch Amplification Mutation Assay for Specific Detection of CS6-Expressing Allelic Variants of Enterotoxigenic Escherichia coli and Its Application in Assessing Diarrheal Cases and Asymptomatic Controls

“…Due to the increase in the incidence of ETEC-mediated diarrheal disease, considerable attention has been paid to the development of simple, sensitive, and less expensive molecular methods for rapid identification of the pathogen. Currently, CFAs are detected by conventional PCR assay, replacing the conventional immunological tests (7,12,13,16,17).The CS6 operon is composed of four genes, cssA, cssB, cssC, and cssD. The structural genes of CS6 are cssA and cssB, which exhibit variation in different CS6-expressing ETEC isolates (16,20).…”

“…Due to the increase in the incidence of ETEC-mediated diarrheal disease, considerable attention has been paid to the development of simple, sensitive, and less expensive molecular methods for rapid identification of the pathogen. Currently, CFAs are detected by conventional PCR assay, replacing the conventional immunological tests (7,12,13,16,17).…”