Prevalence of diarrhegenic serotypes of Escherichia coli in the Cochin estuary, along west coast of India

Prevalence of indicators of faecal pollution such as faecal coliform and faecal streptococci were studied at the Cochin estuary. There was consistently high load of faecal indicator bacteria at all stations. Serotyping of E. coli revealed the presence of diarrhegenic serotypes of E. coli such as enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), enterohemorrhagic E. coli (EHEC) and uropathogenic E. coli (UPEC). The diversity of E. coli serotypes was particularly high as we were able to detect more than 40 serotypes. The E. coli serotypes also showed spatial and temporal variation. Characterisation of faecal streptococci revealed predominance of Streptococcus faecalis subspecies liquefaciens followed by enterococcus group and Streptococcus bovis. Seasonal variation in the prevalence levels of these organisms showed a higher load of the indicator organisms during the monsoon season, especially that of faecal streptococci indicating a higher land run-off during this period. The results of the present investigations reveal the high degree of faecal pollution in the Cochin estuary posing health hazard to those who use this system for fishing and recreation.