Molecular subtyping and erythromycin resistance ofCampylobacterin China

AIMS: To investigate the erythromycin resistance patterns and mechanism for Campylobacter isolates in China. METHODS AND RESULTS: The minimum inhibitory concentrations of erythromycin on 858 Chinese Campylobacter isolates were analysed. PCR and DNA sequencing were used to identify mutations in the 23S rRNA and the presence of the ermB gene in the 158 erythromycin resistance isolates (18·4%). About 83% (131/158) had A2075G mutation in their 23S rRNA; no A2074C/G mutants were found. The ermB gene was identified in 30 Campylobacter coli isolates (19%). Four types of multidrug-resistant gene islands (MDRGIs) were found. Fifty-three types were identified by multilocus sequence typing among the resistant isolates. All isolates of STs 6322 and 1145 had the ermB gene. CONCLUSIONS: The erythromycin resistance rate of Camp. coli (58·56%) was much higher than Campylobacter jejuni (0·67%). The insertion sites between cadF and CCO1582 and between nfsB and cinA on the chromosome might be hot spots for MDRGI transformation. SIGNIFICANCE AND IMPACT OF THE STUDY: Point mutation in domain V of the 23S rRNA and the ermB gene accounted for 100% of the erythromycin resistance of Campylobacter in China.