Purpose: The COVID-19 pandemic and associated non-pharmaceutical interventions (NPIs) have profoundly altered the circulation patterns of respiratory pathogens globally. In the context of the relaxation of these measures, a marked resurgence of Mycoplasma pneumoniae (MP) infections has been observed across China. This study aimed to characterize the epidemiological features and macrolide resistance profile of MP infections among children in Hangzhou during the post-pandemic period (2024 – 2025), providing laboratory surveillance data to inform clinical management. Patients and Methods: We conducted a retrospective analysis of 12,380 respiratory specimens from pediatric patients at Hangzhou Children’s Hospital (March 2024 to December 2025). MP nucleic acid and the 23S rRNA A2063G/A2064G resistance mutations were detected using quantitative PCR. Positivity and resistance rates were analyzed across gender, age, care setting (inpatient/outpatient), and temporal dimensions. Results: The overall MP positivity rate was 19.98% (2,473/12,380). Among positive cases, 86.94% (2,150/2,473) carried resistance mutations-representing one of the highest resistance levels documented globally. Critically, outpatients exhibited significantly higher resistance rates than inpatients (92.13% vs 86.10%; χ 2 =11.89, P 0.05). Age distribution followed a unimodal pattern, peaking in school-aged children (6 – 12 years: 27.90%-39.08%), while resistance rates exceeded 78% across all age groups-notably reaching 92.86% even in infants (< 1 year). Monthly resistance rates in 2024 ranged from 74.89% to 94.20%, escalating to 100% in April and June 2025. Conclusion: This post-pandemic laboratory surveillance reveals alarmingly high and persistently elevated macrolide resistance in pediatric MP infections in Hangzhou, with significantly higher resistance burdens in outpatients. The universal high resistance across all pediatric ages-including infants-suggests widespread community circulation of resistant strains. These findings underscore the urgent need for rapid resistance testing and antimicrobial stewardship programs specifically targeting outpatient pediatric settings in the post-pandemic era. Keywords: Mycoplasma pneumoniae , macrolide resistance, children, outpatient surveillance, post-COVID-19, antimicrobial stewardship, China
Xu et al. (Fri,) studied this question.