Emergence of Novel Macrolide-Resistant Mycoplasma pneumoniae Sequence Type 3 Subclades in Children after COVID-19 Pandemic, Taiwan.

Post-COVID-19 pandemic Mycoplasma pneumoniae resurgences have occurred globally and have been particularly severe in Taiwan. We conducted a multicenter study to assess M. pneumoniae trends in children. Compared with the 2019 peak, 2024 data revealed a doubling of incidence (546/100,000 population), a 2.2-fold increase in intensive care unit admissions (10.9/100,000 population), and a 13.7-fold surge in central nervous system complications (6.1/100,000 population). In a 2023-2024 prospective cohort (n = 226), intensive care unit admission risk factors were neutrophils >7,000/μL (adjusted odds ratio [aOR] 6.2 [95% CI 1.3-29.9]), platelets >400 × 103/μL (aOR 12.5 [95% CI 2.7-57.9]), pleural effusion (aOR 9.7 [95% CI 1.6-58.1]), and central nervous system involvement (aOR 27.9 [95% CI 4.1-188.3]). Phylogenetic analysis of 698 genomes demonstrated that 4 emerging subclades replaced pre-COVID-19 lineages by mid-2024; 1 subclade was associated with severe outcomes, highlighting evolving resistant, neurotropic lineages and calling for enhanced surveillance.