Molecular Mechanisms of Macrolides Resistance in Mycoplasma Pneumoniae

Objective To investigate the molecular mechanisms of macrolides resistance on mycoplasma pneumoniae(MP).Methods Three hundred and seventy throat swab specimens were cultured to isolate MP,clinical isolates were identified by nested polymerase chain reaction(PCR) for MP specific 16S rRNA gene,antibiotic susceptibility test was done to identify macrolide-resistant strains through their minimal inhibitory concentration(MIC) of erythromycin.Beside domainⅤof 23S rRNA,nucleotide sequences of domainⅡof 23S rRNA and ribosomal proteins L4 and L22,which were associated with erythromycin resistance,were amplified by PCR followed by direct automatic sequencing method.The DNA sequences were compared to the corresponding sequences of MP M129 to find molecular mechanisms of drug resis-tance.Results Fifty clinical strains were isolated from 370 throat swab specimens.Of 50 strains,4 strains were susceptible to macrolide,46 strains were macrolide-resistant.MIC of resistant strains to erythromycin were elevated.There was no gene mutation of domainⅡof 23S rRNA in all strains used in the study.About ribosomal protein L4,6 clinical strains and FH apeared mutations C58A,T66G,G81T,C162A and(or)A430G,respectively.About ribosomal protein L22,mutation T508C was observed in all strains except for M129,furthermore,11 clinical strains and FH also appeared mutations C62A,T65A and(or)T279C,respectively.Conclusions Macrolide resistance in MP is very serious,the target mutation in domainⅤof 23S rRNA is predominant mechanism that contribute to the macrolide resistance.Furthermore,there is possibility to induce macrolide-resistant MP in vivo during using macrolide drugs for therapy.