LAUSR

Genomic changes in Mycoplasma pneumoniae caused by adaptation to environmental or ecologic pressures are poorly understood. We collected M. pneumoniae from children who had confirmed pneumonia in Taiwan during 2017–2020. We used whole-genome sequencing to compare these isolates with a worldwide collection of current and historical clinical strains for characterizing population structures. A phylogenetic tree for 284 strains showed that all sequenced strains consisted of 5 clades: T1–1 (sequence type [ST]1), T1–2 (mainly ST3), T1–3 (ST17), T2–1 (mainly ST2), and T2–2 (mainly ST14). We identified a putative recombination block containing 6 genes (MPN366‒371). Macrolide resistance involving 23S rRNA mutations was detected for each clade. Clonal expansion of macrolide resistance occurred mostly within subtype 1 strains, of which clade T1–2 showed the highest recombination rate and genome diversity. Functional characterization of recombined regions provided clarification of the biologic role of these recombination events in the evolution of M. pneumoniae.