Colibacillosis, caused by Escherichia coli (E. coli), has been steadily reducing broiler efficiency and output in the poultry sector. Present research aimed to describe antimicrobial resistance (AMR) and tetA gene mediated tetracycline resistance in E. coli from broiler chicken samples after testing their drug susceptibility and molecular validation. Fifty specimens of liver were retrieved from broiler chicks and E. coli was isolated and purified using MacConkey agar (MCA) and Eosin Methylene Blue agar (EMB) followed by culturing at 37℃ for 24 hours. Several biochemical procedures such as catalase and oxidase tests were performed to confirm bacterial isolates following Gram’s staining presenting morphological assessment. The susceptibility of E. coli was investigated using Amoxicillin (AX) 25 µg, Ciprofloxacin (CIP) 5 µg, Enrofloxacin (ENR) 5 µg, Sulfamethoxazole + Trimethoprim (SXT) 23.75+1.25 µg, Gentamicin (CN) 10 µg, Tetracycline (TE) 30 µg and Cephalexin (CL) 30 µg antibiotic disks placed aseptically at Muller Hinton agar (MHA) plates. The results revealed that 67%, 70%, 39%, 39%, 78%, and 91% of E. coli samples were found resistant for AX, CIP, ENR, SXT, CN and TE, respectively while CL found highly effective. The cultural percentage of isolated E. coli was 92% and a clear depiction of antibiotic-resistant tetA strain of E. coli was validated using polymerase chain reaction (PCR) with 89% resistant percentage.

To Cite This Article: Batool F, Haider A, Ahmad AS, Saddique MA, Waqas MU, Hussain K, Prince K, Ahmed B, Shahbakht RM, Rehman A and Raza MA, 2026. Antimicrobial resistance and tetA gene mediated tetracycline resistance in avian pathogenic Escherichia coli from broiler farms in Multan, Pakistan. Pak Vet J. http://dx.doi.org/10.29261/pakvetj/2026.005