Resistance mechanism of Mycoplasma hominis to quinolones in Chengdu area

Objective To detect the resistance of Mycoplasma hominis to quinolones in Chengdu area, explore resistance mechanism of topoisomerase gene gyrA, gyrB, parC and parE mutations associated with drug resistance and provide epidemiological data. Methods Mycoplasma hominis was identified by 16SrRNA gene sequencing technique and antibiotic susceptibility test was carried out by broth microdilution method. Resistance genes were amplified by PCR, whereas sequence alignment was analyzed by DNAMAN software and BLAST. Results Resistance rates of Mycoplasma hominis to ciprofloxacin, levofloxacin, moxifloxacin and gatifloxacin were 92.4%(61/66), 87.9%(58/66), 71.2%(47/66) and 66.7%(44/66), respectively.Totally 45 strains with different susceptibility to quinolones were screened for amplification and sequencing of topoisomerase genes, of which, 31 strains resistant to moxifloxacin and gatifloxacin harbored GyrA S153L amino acid mutation, 68.9%(31/45), 41 strains resistant to ciprofloxacin and levofloxacin harbored ParC S91I amino acid mutation, 91.1%(41/45). In addition, a new amino acid substitution of ParE A463S was found in 2 high-level resistant strains. No amino acid change was found in GyrB. Conclusions Resistance of Mycoplasma hominis to quinolones is closely associated with amino acid changes caused by mutations in gyrA and parC genes. Different quinolones have different targeting roles and high level resistance is associated with multiple gene mutations.(Chin J Lab Med, 2018, 41: 385-389) Key words: Mycoplasma hominis; Quinolones; Drug resistance, bacterial; DNA Gyrase; DNA Topoisomerase Ⅳ; Mutation