Comparative analysis of the prevalence of antibiotic-resistant Escherichia coli from broilers and roadrunner chickens produced in mixed farming in Seke district

Abstract

Antimicrobial resistance (AMR) within food animal production is a major reservoir of antimicrobial-resistant microorganisms posing a serious threat to public health worldwide. The prevalence, antibiotic susceptibility, and multidrug resistance of Escherichia coli from live broiler and roadrunner chickens from the same farms in Seke District, Zimbabwe, were investigated. A cross-sectional study comparing both live chicken species was conducted. A total of 150 cloacal swab samples were collected from live chickens (75 broiler and 75 roadrunners). Escherichia coli was cultured on MacConkey agar, Blood agar, TBX agar, and Gram staining tests and biochemical tests (motility, citrate, and indole tests). Antimicrobial susceptibility tests using the Kirby-Bauer disc diffusion method were used on selected antibiotics. The most resistant antibiotics in both groups were tetracycline, erythromycin, sulphamethoxazole, and nalidixic acid. The most common antibiotic pattern in all Escherichia coli isolates from chickens (100%) was resistance to tetracycline, nalidixic acid, erythromycin, and sulphamethoxazole, which indicates multidrug resistance (MDR) in resistant Escherichia coli (resistance to three or more antibiotic classes). The resistance rates of Escherichia coli to roadrunners were significantly higher than broilers (p=0.00663). Furthermore, roadrunner E. coli showed lower sensitivity to gentamicin (32% susceptibility) and meropenem (60% susceptibility). The high levels of antimicrobial resistance in both types of chickens from the same farms challenge the notion that raising chickens in free-range systems reduces the risk of antimicrobial resistance. Furthermore, the presence of antimicrobial resistance in both species of chickens indicates the presence of common reservoirs of antimicrobial-resistant pathogens and genes within the environment. Given the threat that antimicrobial-resistant Escherichia coli from chickens poses to public health, interventions must be made within the One Health framework to reduce such risks to the community.