Type â…¡ Topoisomerase Mutations In Clinical Isolates Of Mycoplasma Hominis With Different Phenotypes To Quinolones

ObjectiveMycoplasma hominis is one of microbiotics that responsible for genitalinfections. Furthermore, it has been recognized as being responsible forextragenital infections such as pyelonephritis, postoperative wound infections,and infections in immunosuppressed patients.Mh is naturally resistant to14-and15-membered macrolides. So，thequinolones antibiotics are used in the treatment of infections caused by Mh.Quinolones block DNA replication by inhibiting DNA gyrase activity. Futhermore,a second type II topoisomerase, topoisomerase IV, also is a target of quinolones.Quinolones are frequently used for the treatment of genital tract infections.However, the use of quinolones in the treatment of infections in whichmycoplasma hominis could be involved could lead to the appearance ofquinolone resistance in mycoplasma hominis. But the mechanisms of Mhresistance to quinolones have not yet been elucidated. In this study we havemonitored the antibiotic susceptibility of clinical isolates to quinolones duringthree years. Detected mutation of DNA Gyrase and topoisomerase Ⅳinclinical isolates，and investigate the relation between mutation of mycoplasmahominis Ⅱ type topoisomeraseand the phenotypes to quinolons. Methods21clinical isolates of Mh with different phenotypes of resistance toQuinolones antibiotics were obtained from urogenital specimens from2008to2010in our hospital. The primers of gyrA, gyrB, parC, parE genes highlyconserved region in Mh were deduced by Primer premier5.0software. PCR wascarried out with respective primers, PCR products were sequenced byassistance of Takara. The sequences of the gyrA, gyrB, parC, and parE geneshave been assigned to be compared with standard strain ATCC23114inGenBank. The21mycoplasma hominis clinical strains were characterized fortheir susceptibilities to three quinolones and for the mutation status of their gyrA,gyrB, parC, and parE genes.ResultsRecently three years, sensitivity of clinical isolates to ofloxacin andlevofloxacin is below20%, sensitivity to sparfloxacin is slightly higher than toofloxacin and levofloxacin, which is31.9%.21clinical isolates Mycoplasmahominis was screed,11strains is resistant to sparfloxacin were detected GyrASerine(S)83→Leucine(L), mutation rate is100%, higher than the nonresistancegroup(P<0.01).Although detect some mutation state in gyrB, but did not findamino acid residues variability. For19Mycoplasma hominis isolatesunsusceptible to Ofloxacin and levofloxacin, the rate of Lysine(K)134→Arginine(R) mutation in parC was84.2%, higher than the sensitive group.The rate of Aspartate(D)426→Asparagine(N) mutation in ParE was21.1%, butthere was not significant difference (P>0.05) compared with the sensitive grouppositive rate.ConclusionDNA gyrase S83→L in GyrA is probably related with clinical isolates ofMycoplasma hominis resistance to sparfloxacin; topoisomerase Ⅳ K134→R in ParC is probably related with clinical isolates of Mycoplasma hominis resistanceto ofloxacin and levofloxacin. Here, we infered the DNA gyrase is the primarytarget of sparfloxacin whereas topoisomerase Ⅳ is the primary target ofofloxacin and levofloxacin.