Dev, SidharathSoodan, Maansi2023-02-072023-02-072023-01-06https://krishikosh.egranth.ac.in/handle/1/5810193362The present study investigated the incidence of antimicrobial resistant pathogenic Escherichia coli in poultry reared under intensive and backyard production systems. E. coli isolates were characterized by culture and biochemical methods and were confirmed by PCR. Antimicrobial susceptibility of the recovered isolates was determined for 15 antibiotics from eight classes of antibiotics by disc diffusion method. Virulence factors and plasmid mediated antimicrobial resistance (AMR) determinants were ascertained by PCR based methods. A total of 141 samples including cloacal swabs (n=109) and environmental samples [n=32; water samples (n=16) and litter samples (n=16)] were collected for the isolation and identification of E. coli. Out of the 141 samples, 64 (45.4%, 56 cloacal swabs, 4 water samples and 4 litter samples) samples were from the university poultry farm, CSKHPKV, Palampur and 77 (54.6%, 53 cloacal swabs, 12 water samples and 12 litter samples) were from the backyard poultry units. Overall, E. coli isolations were 90.1 per cent (127/141). 93.8 per cent (60/64) samples from organized rearing system and 87 per cent (67/77) from backyard system were positive for E. coli. 21.3 per cent (27/127) of the tested isolates were detected resistant in this study. AMR was observed for only 3 classes of antibiotics i.e., penicillins (9.4%, 12/127), fluoroquinolones (11%, 14/127) and phenicols (0.8%, 1/127). All (n=127) the isolates from this study were susceptible to aminoglycoside, carbapenem, monobactam and polymyxin classes of antibiotics. Incidence of AMR was significantly higher in E. coli isolates from organized rearing system (30.0%, 18/60) compared to those from backyard units (13.4%, 9/67). No multidrug resistant isolate was detected in this study. None of the tested isolates (n=53) carried stx1 (encoding shiga toxin 1) while, 98.1 per cent (52/53) of the analyzed isolates were positive for stx2 (encoding shiga toxin 2). On analysis of plasmid mediated penicillin resistance, all (n=12) the isolates resistant to penicillin class of antibiotics were positive for blaSHV and two isolates co-expressed blaOXA-1with blaSHV. None of the isolates resistant to penicillin class of antibiotics carried TEM or CTX-M group-1 β-lactamases. 21.4 per cent (3/14) fluoroquinolone resistant isolates were positive for plasmid mediated aac (6’)-Ib (encoding aminoglycoside acetyl transferase). In this study, none of the fluoroquinolone resistant isolates was found to carry qnrA, qnrB, qnrS, qepA and blaCTX-M-1. We recorded significantly higher AMR in E. coli isolates from organized rearing systems compared to backyard systems. Overall, low levels of AMR were recorded. Higher levels of stx2 detection in E. coli isolates indicates a significant public health threat.EnglishThesis