OBJECTIVE: To investigate the association of drug resistance of Mycoplasma pneumoniae (MP) with DNA load and genotypes in children with MP pneumonia. METHODS: A total of 230 children who were hospitalized and diagnosed with MP pneumonia between January 2012 and December 2016 were enrolled. Throat swabs were collected from the 230 children, and a rapid drug sensitivity assay was used to determine the sensitivity of clinical isolates of MP to nine commonly used antibacterial agents. Quantitative real-time PCR was used to measure MP-DNA load in throat swabs. PCR sequencing was used to determine the genotype of 2063 locus of the MP 23S rRNA V domain. RESULTS: Of the 230 children, 86 (37.4%) had genotype A in 2063 locus, 134 (58.3%) had genotype G, 8 (3.5%) had genotype C, and 2 (0.9%) had genotype T. Mutant strains (genotype G+C+T) had a significantly higher MP-DNA load than wild-type strains (genotype A) (P<0.05). The strains resistant to erythromycin, azithromycin, clarithromycin, and clindamycin had a significantly higher MP-DNA load than non-resistant strains (P<0.05). MP had a high drug resistance rate to macrolide antibiotics. More than 60% of the cases with resistance to macrolides were found to have A2063G mutations. MP was rarely resistant to quinolones (less than 2%). CONCLUSIONS: Mutations in 2063 locus of the MP 23S rRNA V domain may result in the resistance of MP to macrolides and the change in DNA load and can be used as a basis for selecting drugs for MP.
OBJECTIVE: To investigate the association of drug resistance of Mycoplasma pneumoniae (MP) with DNA load and genotypes in children with MP pneumonia. METHODS: A total of 230 children who were hospitalized and diagnosed with MP pneumonia between January 2012 and December 2016 were enrolled. Throat swabs were collected from the 230 children, and a rapid drug sensitivity assay was used to determine the sensitivity of clinical isolates of MP to nine commonly used antibacterial agents. Quantitative real-time PCR was used to measure MP-DNA load in throat swabs. PCR sequencing was used to determine the genotype of 2063 locus of the MP 23S rRNA V domain. RESULTS: Of the 230 children, 86 (37.4%) had genotype A in 2063 locus, 134 (58.3%) had genotype G, 8 (3.5%) had genotype C, and 2 (0.9%) had genotype T. Mutant strains (genotype G+C+T) had a significantly higher MP-DNA load than wild-type strains (genotype A) (P<0.05). The strains resistant to erythromycin, azithromycin, clarithromycin, and clindamycin had a significantly higher MP-DNA load than non-resistant strains (P<0.05). MP had a high drug resistance rate to macrolide antibiotics. More than 60% of the cases with resistance to macrolides were found to have A2063G mutations. MP was rarely resistant to quinolones (less than 2%). CONCLUSIONS: Mutations in 2063 locus of the MP 23S rRNA V domain may result in the resistance of MP to macrolides and the change in DNA load and can be used as a basis for selecting drugs for MP.