# Genomic epidemiological analysis reveals new insights into the resurgence of Mycoplasma pneumoniae in China

## TL;DR

This study analyzed the resurgence of Mycoplasma pneumoniae in Beijing, China, using genomic data to understand its spread and genetic changes.

## Contribution

The study reveals that the 2023 M. pneumoniae outbreak in Beijing was due to existing strains, not new variants, with distinct genomic features.

## Key findings

- The 2023 outbreak was caused by pre-existing M. pneumoniae strains, not new variants.
- ST3 and ST14 were the dominant sequence types, with increasing macrolide resistance in ST14.
- Genomic analysis showed high similarity among Beijing strains and distinct regional clustering.

## Abstract

After coronavirus disease 2019 pandemic restrictions, Mycoplasma pneumoniae (M. pneumoniae) re-surged widely across the world. This study aimed to determine the genomic epidemiological characteristics of resurging M. pneumoniae, which has dominated the respiratory infection outbreak in Beijing, China, since mid-September 2023.

M. pneumoniae samples were collected from patients with acute respiratory-tract infections in Beijing in 2018–2023. A total of 160 M. pneumoniae genomes were sequenced via probe-capture-based approach. The genetic features of M. pneumoniae were characterized by multilocus sequence typing and comparative genomic analysis.

In total, 160 patients with M. pneumoniae infections were enrolled. ST3 (n = 93) and ST14 (n = 65) were the predominant sequence types. The macrolide-resistant mutation rate of ST3 was maintained at 100%, whereas that of ST14 increased rapidly. Comparative genomic analysis revealed 99% to > 99% similarity among the Beijing strains from 2023 when aligned to the reference M129 genome. The major variation occurs in the P1 gene. MAUVE indicated a lack of rearrangement, yet it included four subtype-specific insertions and non-conserved hsdS genes. The phylogenetic tree showed that strains from Asia and other world regions clustered into distinct clades, with significant evolutionary differences. Further genomic analyses identified some Asia-dominant genetic variations in genes associated with genome stability, pathogenesis, and drug resistance.

The 2023 outbreak of M. pneumoniae was not attributable to a novel variant but stemmed from the resurgence of the pre-existing strains. Our genomic epidemiological findings demonstrated that the endemic strains in different regions exhibit distinct genomic characteristics, associated with genomic stability.