Emerging <i>erm</i> (B)-Mediated Macrolide Resistance Associated with Novel Multidrug Resistance Genomic Islands in <i>Campylobacter</i>

Abstract

The rapid dissemination of the macrolide resistance gene <i>erm</i>(B) will likely compromise the efficacy of macrolides as the treatment of choice for campylobacteriosis. More importantly, <i>erm</i>(B) is always associated with several multidrug resistance genomic islands (MDRGIs), which confer resistance to multiple other antimicrobials. Continuous monitoring of the emergence of <i>erm</i>(B) and analysis of its associated genetic environments are crucial for our understanding of macrolide resistance in <i>Campylobacter</i> In this study, 290 <i>Campylobacter</i> isolates (216 <i>Campylobacter coli</i> isolates and 74 <i>Campylobacter jejuni</i> isolates) were obtained from 1,039 fecal samples collected in 2016 from pigs and chickens from three regions of China (344 samples from Guangdong, 335 samples from Shanghai, and 360 samples from Shandong). Overall, 74 isolates (72 <i>C. coli</i> isolates and 2 <i>C. jejuni</i> isolates<b>)</b> were PCR positive for <i>erm</i>(B). Combined with data from previous years, we observed a trend of increasing prevalence of <i>erm</i>(B) in <i>C. coli</i> Pulsed-field gel electrophoresis analyses suggested that both clonal expansion and horizontal transmission were involved in the dissemination of <i>erm</i>(B) in <i>C. coli</i>, and three novel types of <i>erm</i>(B)-associated MDRGIs were identified among the isolates. Furthermore, 2 <i>erm</i>(B)-harboring <i>C. jejuni</i> isolates also contained an aminoglycoside resistance genomic island and a multidrug-resistance-enhancing efflux pump, encoded by RE-<i>cmeABC</i> 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 <i>erm</i>(B)-associated MDRGIs might further limit treatment options for campylobacteriosis.