Recent Trend of Antimicrobial Susceptibility among Mycoplasma pneumoniae Isolated from Japanese Children

Macrolide-resistant Mycoplasma pneumoniae (MRMP) infections have become increasingly prevalent, especially in East Asia. Whereas MRMP strains have point mutations that are implicated in conferring resistance, monitoring the antibiotic susceptibility of M. pneumoniae and identifying mutations in the resistant strains is crucial for effective disease management. Therefore, we investigated antimicrobial susceptibilities among M. pneumoniae isolates obtained from Japanese children since 2011. To establish the current susceptibility trend, we analyzed the minimum inhibitory concentrations (MICs) of M. pneumoniae in recent years (2017-2020) in comparison with past data. Our observation of 122 M. pneumoniae strains suggested that 76 were macrolide-susceptible M. pneumoniae (MSMP) and 46 were macrolide-resistant. The MIC ranges (mu g/mL) of clarithromycin (CAM), azithromycin (AZM), tosufloxacin (TFLX), and minocycline (MINO) to all M. pneumoniae isolates were 0.001->128, 0.00012->128, 0.25-0.5, and 0.125-4 mu g/mL, respectively. None of the strains was resistant to TFLX or MINO. The MIC distributions of CAM and AZM to MSMP and MINO to all M. pneumoniae isolates were significantly lower, but that of TFLX was significantly higher than that reported in all previous data concordant with the amount of recent antimicrobial use. Therefore, continuation of appropriate antimicrobial use for M. pneumoniae infection is important.

Automated summary

Macrolide-resistant Mycoplasma pneumoniae (MRMP) infections are becoming more common in East Asia. Monitoring antibiotic susceptibility and identifying mutations in resistant strains is crucial for managing the disease effectively. A study in Japan found that out of 122 M. pneumoniae strains, 76 were susceptible to macrolides and 46 were resistant. None of the strains showed resistance to tosufloxacin or minocycline. The study also revealed a decrease in susceptibility to clarithromycin and azithromycin, and an increase in susceptibility to tosufloxacin.