Serological diversity, molecular characterisation and antimicrobial sensitivity of avian pathogenic Escherichia coli (APEC) isolates from broiler chickens in Kashmir, India.

The present study has determined the serological diversity, virulence-gene profile and in vitro antibiogram of avian pathogenic Escherichia coli (APEC) isolates from broiler chickens in India suspected to have died of colibacillosis. The virulence-gene profile of APEC was compared with that of the Escherichia coli isolates from faeces of apparently healthy chickens, called avian faecal E. coli (AFEC). In total, 90 representative isolates of APEC and 63 isolates of AFEC were investigated in the present study. The APEC were typed into 19 serogroups, while some isolates were rough and could not be typed. Most prevalent serogroup was O2 (24.44%). Among the eight virulence genes studied, the prevalence of seven genes (iss , iucD , tsh , cva / cvi , irp2 , papC and vat) was significantly higher in APEC than in AFEC isolates. However, there was no significant difference between APEC and AFEC isolates for possession of astA gene. The most frequent gene detected among the two groups of organisms was iss , which was present in 98.88% and 44.44% of APEC and AFEC isolates respectively. The in vitro antibiogram showed that the majority (96.6%) of APEC isolates were resistant to tetracycline, while 82.2% were resistant to cephalexin, 78.8% to cotrimoxazole, 68.8% to streptomycin and 63.3% to ampicillin. However, most of them (84.45%) were sensitive to gentamicin. Thus, it is concluded that APEC from the broiler chickens carried putative virulence genes that attributed to their pathogenicity. Furthermore, the majority of APEC isolates were found to be multi-drug resistant, which, in addition to leading treatment failures in poultry, poses a public health threat. Avian colibacillosis caused by avian pathogenic Escherichia coli (APEC) is responsible for heavy economic losses to commercial broiler farmers. The present work investigated APEC isolates and their comparison with avian faecal E. coli (AFEC) isolates. The results suggest that virulence genes were more prevalent in APEC than in AFEC and the majority of the APEC isolates exhibited a multi drug resistant pattern. The present study will serve as a reference study for future work on APEC and extra intestinal pathogenic E. coli. [ABSTRACT FROM AUTHOR]