IN VITRO COMPARATIVE EFFICACY OF SELECTED ANTIBIOTICS AGAINST ESCHERICHIA COLI ISOLATED FROM BROILERS

Abstract

This study aimed to evaluate and compare the in vitro antibacterial activity of four commonly used antibiotics—Levofloxacin, Cefixime, Vibramycin, and Amoxyl—against Escherichia coli (E. coli) isolated from broiler chickens in the Kohat District of Khyber Pakhtunkhwa, Pakistan. Using standard microbiological techniques, E. coli was successfully isolated and confirmed through selective media, Gram staining, and biochemical tests including citrate, catalase, and oxidase assays. Antibiotic sensitivity testing was conducted using the agar well diffusion method at a uniform concentration of 0.25 mg/ml for all antibiotics. Levofloxacin exhibited the highest antibacterial activity with an average inhibition zone of 37 mm, followed by Cefixime (35 mm), Vibramycin (31.33 mm), and Amoxyl (16 mm), indicating variable efficacy among the tested agents. The results confirm Levofloxacin's superior effectiveness, with Cefixime and Vibramycin as viable alternatives, while Amoxyl showed limited efficacy. No resistant E. coli strains were observed against the tested antibiotics, suggesting their continued relevance for clinical use in poultry. This study highlights the importance of antibiotic sensitivity profiling to inform effective treatment strategies in broiler management and address the emerging concern of antimicrobial resistance