Prevalence and antibiotic resistance of extended spectrum β-lactamase producing Escherichia coli in sheep and slaughterhouse environment in Kayseri, Türkiye: A special focus on β-lactamase genes.

Antimicrobial resistance is a worldwide threat that causes serious health problems in both humans and animals. There is limited information regarding the prevalence of extended-spectrum β-lactamase (ESBL) producing Escherichia coli in small ruminants. The purpose of this study was to determine the prevalence, and antibiotic resistance profiles of ESBL E. coli in sheep and the slaughterhouse environment in Kayseri, Türkiye. E. coli isolates were further screened for the presence of ESBL and carbapenemase-encoding genes (bla_CTX-M, bla_SHV, bla_TEM, bla_KPC, bla_NDM, and bla_OXA-48). A year-long study was conducted to include all seasons. Samples from sheep included feces, carcass swabs, paddock feces, and cecum content (n = 108) while samples from the slaughterhouse included surface and wastewater samples (n = 76). McConkey agar containing 4 µg/ml of cefotaxime was used to isolate ESBL E. coli. A double disk-diffusion test was performed to confirm β-lactamase production. Using the conventional method, 40.7% (44/108) isolates from sheep and 23.7% (18/76) isolates from environmental samples were tested to be positive. The prevalence of ESBL E. coli in sheep samples was significantly higher in summer (70.4%) than in spring (40.7%), autumn (33.3%), and winter (18.5%) (P₁ < 0.001). In regard to β-lactamase genes; bla_TEM 62 (100%), bla_CTX-M 56 (90.3%), and bla_SHV 2 (3.2%) were found positive. Of the 15 (24.2%) isolates tested to be positive for the bla_OXA-48 gene, none had the ability to produce carbapenamase. Most isolates harbored multiple genes with bla_TEM + bla_CTX-M was observed in 40 (64.5%), bla_TEM + bla_CTX-M + bla_OXA-48 in 13 (20.9%), and bla_TEM + bla_CTX-M + bla_OXA-48 + bla_SHV in 2 isolates (3.2%). Based on antibiotic resistance testing, all ESBL-producing isolates were found to be resistant to ampicilin and ceftazidime. Resistance to cloramphenicol 36 (58.1%) was evidently followed by gentamicin 27 (43.5%), nalidixic acid 27 (43.5%), ciprofloxacin 25 (40.3%), amoxicillin-clavulanic acid 7 (11.3%), azithromycin 6 (9.7%) and imipenem 4 (6.5%). The results indicated 43 (69.4%) isolates to be multidrug-resistant.