Mycoplasma pneumoniae Infections Among Children and Adolescents in Korea, 2014-2024.

Background: Mycoplasma pneumoniae (MP) is the most common cause of community-acquired bacterial pneumonia in children. Macrolides are used as the first-line treatment for MP infection, but resistance has increased significantly over the past few decades, making treatment difficult. This study examines the prevalence of M. pneumoniae infections and macrolide-resistant M. pneumoniae (MRMP) rates in Korean children across three recent epidemics in Korea between 2014 and 2024.

Methods: Data from Green Cross Laboratories on M. pneumoniae polymerase chain reaction (PCR) and macrolide-resistance tests were analyzed from January 2014 to March 2024, including 425,079 MP PCR tests and 11,206 resistance tests (macrolide-resistance testing began in 2019). We examined M. pneumoniae-positive rates by age and compared age composition to the epidemic and non-epidemic periods using Cochran-Armitage trend tests and also examined differences in MRMP positive rates by year, epidemic status, sex, age group, and region using the χ² test.

Results: Three epidemics of M. pneumoniae infection were identified in 2015/16, 2019/20, and 2023/24, with seasonal peaks between the third and fourth quarter of each starting epidemic year and the highest M. pneumoniae-positive rates in children aged 7 to 9 years. There were significant differences in the proportion of children aged 12 years or younger between epidemic and non-epidemic periods (P < 0.001 for two epidemics and 0.027 for one). MRMP PCR positive rates for A2063G and A2064G mutations were 76.6% and 0.7%, respectively, with a notable increase in A2063G rates from 2019/20 to 2023/24, along with a significant decrease as age increased.

Conclusion: The findings indicate a significant rise in M. pneumoniae infections among Korean children, especially those aged 12 years or younger, suggesting a nationwide epidemic. The increase in A2063G mutation rates underscores the need for monitoring antibiotic resistance and further research into resistance factors for future epidemic responses.