Serotypes of enteropathogenic Escherichia coli isolated from children under 5 years of age

ABSTRACT

The purpose of this study was to find out the frequency of different serotypes of enteropathogenic Escherichia coli [EPEC] among healthy/ diarrheal cases. A total of 191 strains, 111 from diarrheal and 80 from asymptomatic persons were examined. Determination of the EPEC serogroups was performed by agglutination tests using polyvalent and monovalent O antiserum. PCR-RFLP analysis of the flagellin-encoding [fliC] gene and agglutination tests using polyvalent and monovalent sera against H antigens [H1 to H56] according to the instructions of the manufacturer was performed. Seventeen [8.9%] strains were non-motile and untypable with conventional serotyping method that showed as H[-]. Forty-three fliC restriction patterns were found for motile and non-motile serotypes. Each motile serotype was characterized by one or two fliC specific restriction patterns. O142H48 [6.8%], O86H48 [6.35], O111H21[4.7%] and O127H21 [4.2%] were the most prevalent serotypes, and O55H12/45, O86H48, O127H21, O142H48, O126H19 serotypes were the most frequently agents in diarrheal cases, compared to asymptomatic children [P<0.05]. There were common EPEC serotypes in diarrheal and asymptomatic children, however some serotypes either found only in diarrheal cases or isolated from asymptomatic persons. Some serotypes were isolated more frequently from diarrheal cases than asymptomatic persons. The conventional serological method using antisera is the basis for the H typing system in E-coli, but it is impossible to serotype non-motile bacteria. PCR-RFLP analysis of fliC gene is a practical method in identifying the H variant in motile and non-motile EPEC serotypes and is useful for epidemiological studies