Mutations in domain V of Mycoplasma pneumoniae 23S rRNA are not associated with clinical characteristics of M. pneumoniae pneumonia in children: a case control study

Background Mycoplasma pneumoniae (MP) is a common agent of community-acquired pneumonia in children and young adults that can lead to refractory or persistent Mycoplasma pneumoniae pneumonia (MPP). Macrolide-resistant MP harbors point mutations in domain V of 23S ribosomal Ribonucleic Acid (rRNA) with substitutions detected at positions 2063, 2064, 2067 and 2617. This study aims to investigate the prevalence and clinical characteristics of mutations in domain V of MP 23S rRNA. Methods We sequenced the 23S rRNA domain V of MP strains collected from children with MPP. Clinical and laboratory data were also obtained, including gender, age, duration of fever, duration of fever after the start of macrolide therapy, MP-Deoxyribonucleic Acid (DNA) load at enrollment, leukocyte count, neutrophil, and lymphocyte count, immunomodulators treatment and pulmonary complications. Results Of 276 strains, 255 (92.39 %) harbored A to G transition at the position 2063 (A2063G), and 21 (7.61 %) were not mutated. There were no significant differences in gender, age, duration of fever, duration of fever after the start of macrolide therapy, MP-DNA load at enrollment, hospitalization days, lymphocyte count and pulmonary complications when patients were stratified based on the presence or absence of domain V mutations. We also found that children with refractory MPP experienced higher MP-DNA load than the non-refractory MPP, but the prevalence of domain V mutations was no statistical difference. Conclusions We found that clinical MP strains harbored very high mutation rate in 23S rRNA domain V, especially A2063G mutation. However, these mutations were not associated with clinical symptoms, laboratory results, pulmonary complications and development of refractory MPP. Instead, MP-DNA load was significantly different between refractory and non-refractory MPP.