Study on the Distribution of Esbl Producing E. Coli in Poultry Under Different Rearing Patterns

Abstract

In view of rising importance of extended spectrum beta-lactamase (ESBL) driven antimicrobial resistance in gram negative bacteria, the present study was undertaken to study the distribution of ESBL producing E. coli in poultry under different rearing patterns. A total of 208 samples from diverse sources including faecal, environmental, feed and water, comprising of 66 from layer farms, 69 from broiler farms and 73 from backyard poultry setup were collected and processed for isolation of ESBL producing E. coli. At first pure culture of E. coli of each isolate was obtained by cultural methods. Of the 208 samples, 179 and 160 were positive for E. coli by cultural and PCR based test, respectively. Further, evaluation of the isolates for ESBL production was done by phenotypic and genotypic methods. Improvised media employed for selective isolation of ESBL detected 53.63 % (96/ 179) ESBL E. coli. Double disk diffusion test confirmed ESBL production by 44.69 % (80/ 179) of E. coli isolates. Highest prevalence was shown in layer farms (48.48 %) followed by broiler farms (36.23 %) and backyard poultry (31.50 %) by this test. Evaluation of sensitivity to 3rd and 4th generation cephalosporin and monobactam revealed nearly 17.3 % of isolates to be totally resistant to all the 6 antibiotics used. Only 11.7 % E. coli isolates were sensitive to all the cephalosporins and monobactam. Highest resistance was reported for cefixime (58.10 %) followed by cefotaxime (48.60 %). E-test could detect only 7.26 % (13/ 80). Optimization of PCR protocols for detection of two ESBL genes blaTEM and blaCTX-M yielded specific PCR amplicons of 800 bp and 688 bp, respectively. Screening of ESBL producing isolates revealed that 37.5 % and 11. 25 % of isolates were positive for blaTEM and blaCTX-M gene, respectively. Highest prevalence of ESBL genes was in layer farms 28.78 % followed by backyard poultry 16.43 % and broiler farms 11.59 %. High prevalence of ESBL in backyard poultry is unusual finding. However, blaTEM was the most abundant ESBLs type in this region. Antimicrobial sensitivity testing and multi-drug resistance scoring indicated that most of the isolates were multidrug resistant. Nearly 100 % resistance was reported against carbenicillin and erythromycin although high sensitivity was seen against imipenem. High resistance of isolates for Amoxiclav (92.73%), Nalidixic acid (90.50%), Ampicillin (86.03%), Tetracycline (80.44%), Co-trimoxazole (71.50%), Ciprofloxacin (58.65%), Kanamycin (49.72%) while low resistance was seen for Chloramphenicol (7.26%) and Gentamicin (2.7%).