Abstract #T62

# T62
Extended-spectrum cephalosporin, carbapenem, and fluoroquinolone-resistant gram-negative coliform bacteria present on equine environmental surfaces.
Rachael Adams*2, Dixie Mollenkopf1, Dimitria Mathys1, Joshua Daniels1, Thomas Wittum1, 1The Ohio State University College of Veterinary Medicine, Columbus, OH, 2The Ohio State University College of Food, Agricultural, and Environmental Sciences, Columbus, OH.

Antimicrobial resistant bacteria are a rapidly growing concern in human and veterinary medicine. The rising prevalence of extended spectrum β-lactamase (ESBL), AmpC β-lactamase, carbapenemase (CRE), and fluoroquinolone-resistant Enterobacteriaceae continually decreases the efficiency of vital antibiotics. Moreover, antibiotic resistant enteric bacteria are zoonotic and can be transmitted between horses and people. Our objective was to evaluate the prevalence of antibiotic resistant bacteria on human contact surfaces in equine environments. Environmental surfaces in 20 Ohio equine barns were sampled using 2 electro-static cloths (Swiffer), yielding a total of 242 samples. Samples were phenotypically screened for AmpC, ESBL, CRE, and fluoroquinolone resistance using selective media. To select for cephalosporinase phenotypes, samples were incubated at 37°C in nutrient broth with 2 μg/mL cefotaxime. This broth was aseptically inoculated to MacConkey agar with 8 μg/mL cefoxitin, 4 μg/mL cefepime, and 1 μg/mL meropenem to detect AmpC, ESBL, and CRE phenotypes, respectively. Additionally, samples were incubated in nutrient broth with 16 μg/mL naladixic acid and then inoculated to MacConkey agar with 16 μg/mL naladixic acid and 2 μg/mL ciprofloxacin to detect fluoroquinolone resistance phenotypes. Genotypes were confirmed using standard PCR techniques. Of the coliform bacteria isolated from each surface, 49 (24.5%) were cefoxitin resistant, 25 (12.5%) were naladixic acid resistant, 13 (6.5%) were cefepime resistant, and 9 (4.5%) were ciprofloxacin resistant. Drains and wash stalls were most commonly contaminated at 17 resistant isolates, followed by handles of mucky equipment at 15 resistant isolates. These results indicate that equine environmental surfaces are contaminated with resistant bacteria that can potentially be transmitted between human and horse populations. Furthermore, detecting these bacteria on common human contact surfaces suggests that the environment can serve as a reservoir for antibiotic resistance genes. Identifying interventions to lower the prevalence of antibiotic resistant bacteria in equine environments will protect both animal and public health.

Key Words: antibiotic resistance, equine, environmental