Molecular characterization of STEC isolated from Ducks and its relation to ESBL production

The ESBL producing genes are responsible for bacterial resistance to number of antibiotics whereas Shiga toxin producing genes are responsible for bacterial virulence. The association between ESBL producing genes and Shiga toxin producing E. coli (STEC) may pose bigger threat in the battle of antibiotic resistance. This study was conducted to determine the prevalence of Shiga-toxin-producing Escherichia coli (STEC) in ducks reared in organized and unorganized sectors from different agro climatic zones of West Bengal, India and to study their relationship with extended spectrum beta-lactamase (ESBL) production. Total 202 cloacal swab samples were collected from both indigenous ducks reared in backyards sector (110 samples) and Khaki Campbell Ducks reared in organized farm (92 samples). Initially the samples were screened for detection of E. coli on the basis of their cultural, morphological and biochemical properties followed by PCR confirmation for E. coli 16S rRNA. E. coli isolates were subjected to multiplex PCR to detect the presence of shiga toxin producing genes such as stx1, stx2, eaeA and ehxA. STEC isolates were screened phenotypically for production of ESBL and ACBL by double disk diffusion method and subsequently PCR detection for blaCTX-M, blaTEM, blaSHV and blaAmpC genes were performed. Serotyping of all the STEC was also done. Out of 202 samples total 109 were confirmed to be E. coli positive. Out of them total 27 (24.77 %) E. coli isolates were detected to be positive for STEC. Higher prevalence of STEC was observed in unorganized sector compared to the organized sector. Positive association (P < 0.05) was observed between STEC and ESBL production. This study indicates that the duck may play an important role in transmission of Siga-toxin-producing E. coli (STEC) as well as antibiotic resistance genes to human beings, other birds, animals and environment also.