Emerging erm (B)-mediated macrolide resistance associated with novel MDRGIs in Campylobacter .

The rapid dissemination of macrolide resistance gene erm (B) will likely compromise the efficacy of macrolides as the treatment of choice for campylobacteriosis. More importantly, erm (B) is always associated with several multidrug resistance genomic islands (MDRGIs), which confer resistance to multiple other antimicrobials. Continuous monitoring of the emergence of erm (B) and analysis of its associated genetic environments is crucial to our understanding of macrolide resistance in Campylobacter In this study, 290 Campylobacter isolates (216 C. coli and 74 C. jejuni ) were obtained from 1039 fecal samples collected from pigs and chickens from three regions of China (344 from Guangdong, 335 from Shanghai, and 360 from Shandong) in 2016. Overall, 74 isolates (72 C. coli and 2 C. jejuni ) were PCR-positive for erm (B). Combined with data from previous years, we observed an increasing trend in the prevalence of erm (B) in C. coli Pulsed-field gel electrophoresis analyses suggested that both clonal expansion and horizontal transmission were involved in the dissemination of erm (B) in C. coli , and three novel types of erm (B)-associated MDRGI were identified among the isolates. Furthermore, two erm (B)-harboring C. jejuni isolates also contained an aminoglycoside resistance genomic island and a multidrug resistance-enhancing efflux pump, encoded by RE- cmeABC Antimicrobial susceptibility testing showed that most of the isolates were resistant to all clinically-important antimicrobial agents used for the treatment of campylobacteriosis. These findings suggest that the increasing prevalence of erm (B)-associated MDRGIs might further limit treatment options for campylobacteriosis.