The present study was carried out with an objective to evaluate antimicrobial resistant pathogenic E. coli from selected broiler production systems in and around Parbhani city. A total of 216 samples comprising 36 various contamination sources from each farm were collected from six broiler units. The initial isolation of E. coli was done on EMB and MacConkey agar. On morphological and biochemical tests, 105(48.61%) isolates were preliminary confirmed as E. coli. Out of 105 preliminary confirmed isolates, randomly selected 55 isolates were further confirmed as E. coli by PCR targeting 16S rRNA gene and phenotypically marked as pathogenic by Congo Red Binding Assay. Out of 55 confirmed isolates, 20 randomly selected isolates were tested against commonly used 15 antimicrobials. antimicrobial susceptibility testing revealed higher resistance against Erythromycin (100%), Cephalothin (95%), Tetracycline (90%), Nalidixic acid (90%) Ceftazidime (85%), Cefotaxime (85%), Amikacin (80%), Gentamicin (75%), Amoxiclav (75%), Ciprofloxacin (70%), Enrofloxacin (70%), Levofloxacin (60%) and sensitivity observed against ampicillin/Sulbactam (85%), Amoxicillin/sulbactam (75%) and Chloramphenicol (50%). The average multiple antimicrobial resistance index of 20 isolates was 0.7. These 20 isolates subjected to genotypic antimicrobial resistance by PCR and found that 85 and 80% isolates expressed tet A and blaTEM genes which indicates resistance against Tetracycline and β-lactam antimicrobials. The study concludes that higher occurrence of multiple antimicrobial resistant E. coli with genotypic characteristics in broiler farms may pose high risk to human and animal health, therefore regional surveillance on use of antimicrobials and studies on antimicrobial resistant bacteria in broiler needs to be conducted regularly.

Highlights

• All the E. coli isolates of poultry found pathogenic with Congo red binding assay.
• tet A and blaTEM genes were observed in E. coli isolated from broiler poultry farming system.
• The average MAR index of E. coli isolates was 0.7 which indicates that isolates were originated from high-risk sources and resistant against multiple antibiotics.