Mycoplasma pneumoniae 23S rRNA Gene Mutations and Mechanisms of Macrolide Resistance

Resistant strains of Mycoplasma pneumoniae lead to antibiotic inefficacy. The relationship between M pneumoniae 23S rRNA (GenBank: X68422.1) gene mutations and macrolide resistance phenotype has not been fully established, to our knowledge. In this study, we isolated and cultured macrolide-resistant strains of M pneumoniae and tested them for 23S rRNA gene mutations. Throat swab samples from patients (n = 800) with community-acquired respiratory tract infections were isolated by nested PCR for the molecular identification of clinical isolates. An in vitro drug sensitivity test was performed on clinical isolates for macrolide antibiotic efficacy. The minimum inhibitory concentration (MIC) was used to select resistant strains. Resistant strains of 23S rRNA were sequenced and compared with the sequences of standard macrolidesensitive M129 strains by comparative sequence analysis, focusing the analysis on mutations linked to the drug-resistance phenotype. One hundred M pneumoniae strains were isolated, of which 82 strains were macrolide sensitive and 18 strains were resistant. Mutations were identified in 16 of the 18 macrolide-resistant strains. The following mutations were detected: A2063G, A2064G, C2617G, and A2067G. Of these mutations, A2063G exhibited 14-ring macrolide resistance, A2064G exhibited 14- and 16-ring macrolide resistance, C2617G demonstrated 14- and 15-ring macrolide resistance, and A2067G demonstrated josamycin resistance. M pneumoniae resistance to macrolide antibiotics is a serious clinical issue: our results indicate that 23S rRNA mutations are associated with drug resistance. By analysis of the 23S rRNA mutation and resistance phenotype, our understanding of the clinical drug resistance of M pneumoniae can aid in the rational selection and application of antibiotics for optimal therapeutic treatments.