Predominance of "atypical" enteroaggregative escherichia coli among human, animal, foods and associated environmental sources.

Background: Infectious diarrhoea particularly due to pathogenic bacteria is a major health problem in developing countries, including India. Despite significant reports of diarrhoeagenic Escherichia coli (DEC) pathotypes across the globe, there is paucity of studies which reveal their relatedness with respect to their isolation from different sources. This present study determines isolation and identification of DEC pathotypes from different sources, their genetic characterization and antibiogram sensitivity profiling. Methods & Materials: A total of 336 samples comprising of diarrhoeic stool samples from infants (n = 103), young animals (n = 106), foods and associated environmental sources (n = 127) were screened for E. coli. The identified E. coli were confirmed as DEC pathotypes by using PCR based assays. These isolates were further studied for their genetic diversity using Pulse Field Gel Electrophoresis (PFGE) subtyping tool and their antibiogram profilewas determined against seven commonly used drugs. Results: Of the four DEC pathotypes investigated, Enteroaggregative E. coli (EAEC) was found to be the predominant pathogen with an isolation rate of 16.50% from infants, 17.92% from young animals and 10.24% from foods and environmental sources. These EAEC isolates, on further characterization revealed predominance of 'atypical' EAEC, with an isolation rate of 10.68% from infants, 15.09% from young animals and 10.24% from foods and associated environmental sources. On PFGE analysis, discrimination was also evident withinDECpathotypes, as only closely relatedEAECisolates clustered together irrespective of their source of isolation. Further, higher antibiotic resistance pattern was observed among the isolated DEC pathotypes as almost 86.44% of isolates were found to be resistant against ≥3 tested drugs. Conclusion: EAEC pathotype in particular 'atypical' strains were found to be the predominant pathogen. On PFGE analysis, sharing and circulation of EAEC isolates between human and animal, including foods and associated environmental sources was evident. Besides this, an alarming antimicrobial resistance profile was observed for majority of the recovered DEC pathotype isolates. [ABSTRACT FROM AUTHOR]