Sero-characterization of intestinal and extra-intestinal Escherichia coli (E. coli) isolates from different geographical locations in India

Serotyping is the most widely used epidemiological marker to characterize pathogenic E. coli. Pathogenic E. coli is diverse as different serotypes are known to be prevalent in different area. Certain serotypes are known to be closely associated with pathotypes especially among diarrheagenic E. coli. Analysis of E. coli serotypes prevalence and its distribution pattern in different geographical area is important from better understanding its epidemiology and better control and management of E. coli diarrhea and non-intestinal infections. Present study was carried out to study prevalence of various “O”serogroups in clinical E. coli isolates in India and its distribution in different geographical locations of the country. A total of 783 clinical isolates suspected to be E. coli comprising of 437 Intestinal (human diarrheal) and 346 extra-intestinal isolates (human UTI) were biotyped using conventional Biotyping method to confirm isolates as E. coli. A total 534 confirmed E. coli isolates were sero-typed using specific anti E. coli “O” antiserum by micro titer plate agglutination assay. The 534 E. coli isolates were found to be clustered over 36 different groups. O8, O11, O22, O126, O88, O83, O35, O7, O149 and O141 being the most frequently detected “O” serogroups. Serogroup O157 was also detected in only seven isolates. Big six serotypes were not detected. This study indicates that diverse E. coli serotypes are in circulation in the country. With very low frequency of serogroup O157 frequently associated with EHEC/STEC.