Emergence of the Phenicol Exporter Gene fexA in Campylobacter coli and Campylobacter jejuni of Animal Origin

Abstract

Bacteria of the genus Campylobacter are major foodborne pathogens that have become increasingly resistant to clinically important antimicrobial agents (1). In China, Campylobacter jejuni is the main cause of human Campylobacter infections, whereas Campylobacter coli isolates exhibit a distinctly higher multidrug resistance rate. Fluoroquinolones and macrolides are the most frequently used antimicrobial agents to treat Campylobacter infections (2). Florfenicol has been widely used in food animals to treat bacterial infections for many years (3). Although it was not the treatment of choice for Campylobacter infections, the resistance rate of florfenicol in Campylobacter spp. of animal origin in China has increased in the past few years (4). The resistance-enhancing efflux pump CmeABC (RE-CmeABC) and the rRNA methyltransferase Cfr(C) were the only two identified transferable resistance proteins that conferred low-level florfenicol resistance (MIC, ≤16 mg/liter) in Campylobacter (5, 6). In this study, we identified for the first time the florfenicol resistance gene fexA in Campylobacter spp. of animal origin and investigated its genetic environment.