Macrolide resistance rate and antimicrobial selection in pediatric Mycoplasma pneumoniae infection during 2024.

INTRODUCTION: A Mycoplasma pneumoniae (MP) infection outbreak occurred in Japan in 2024. Macrolides (MLs) are first-line antibiotics for MP infections; however, ML resistance rates vary by region and time of year. In recent years, point-of-care Quenching Probe PCR (QP-PCR) assays have enabled the detection of MP and macrolide resistance mutations. We aimed to determine the impact of rapid diagnosis by QP-PCR on clinical outcomes, the ML resistance rate, and the therapeutic efficacy of MLs, minocycline (MINO) and tosufloxacin (TFLX) in pediatric patients with MP infection in 2024. METHODS: This single-center retrospective observational study was conducted from January to December 2024. A total of 206 pediatric patients with MP infection and ML susceptibility determined by QP-PCR were included. The primary outcome was fever duration. RESULTS: MLs susceptible MP (MSMP) was identified in 132 (64%) patients and MLs resistant MP (MRMP) in 74 (36%) patients. In the MSMP, the time to defervescence after the initiation of susceptible antibiotics was shorter with MLs than with TFLX (1 vs. 5 days, p < 0.001). Among patients with MRMP aged ≥8 years, it was shorter in MINO than with TFLX (1 vs. 3 days, p = 0.002). QP-PCR-guided antibiotic initiation group had a shorter total fever duration compared with the empirical antibiotic initiation followed by QP-PCR-guided antibiotic modification group (MSMP; 6 [4-7] vs. 7 [6-9] days, p <0.001, MRMP; 5 [3-7.75] vs. 8 [5-9] days, p =0.005). CONCLUSIONS: Early diagnosis using QP-PCR may contribute to shortening the duration of fever.