Molecular epidemiology and genomic characterization of postpandemic macrolide-resistant Mycoplasma pneumoniae in hospitalized children.

OBJECTIVES

A marked resurgence of macrolide-resistant Mycoplasma pneumoniae (MP) was observed in China following relaxation of COVID-19 nonpharmaceutical interventions (NPIs). We characterized the molecular and genomic features of macrolide-resistant isolates in hospitalized children.

METHODS

We retrospectively analyzed 3348 pediatric MP cases in a tertiary hospital in Zhengzhou (2017-2023). Seventy-two MP-positive BALF (bronchoalveolar lavage fluid) specimens collected during the NPI (2020-2022) and post-NPI (2023) periods were randomly selected for culture, genotyping, and resistance mutation analysis; 23 isolates underwent antimicrobial susceptibility testing and whole-genome sequencing, with comparison to 313 global genomes.

RESULTS

MP positivity peaked at 86.2% in late 2023, indicating a postpandemic resurgence. Genotype 1 predominated, and all isolates carried the A2063G mutation, conferring macrolide resistance. Phenotypic testing confirmed universal resistance to macrolides, while susceptibility to fluoroquinolones and tetracyclines was retained. Phylogenetic analysis showed clustering within established lineages and close relatedness to prepandemic strains, with no evidence of novel variant emergence.

CONCLUSIONS

The postpandemic resurgence of MP in Zhengzhou was driven by macrolide-resistant strains belonging to established lineages. These findings highlight the importance of molecular surveillance and routine resistance testing in clinical microbiology laboratories.