Analysis of Drug-Resistant Bacteria Seasonality in Japan Using Financial Time Series Analysis Method: A Nationwide Longitudinal Study.

Bacterial infections exhibit seasonal variation, particularly in respiratory pathogens; however, whether similar trends exist for bacterial infections and resistance in Japan is unclear. This study examined seasonal and annual patterns of bacterial isolation rates and antimicrobial resistance in Japanese hospitals, utilizing data from the Ministry of Health, Labour, and Welfare's Nosocomial Infection Control Surveillance Project (JANIS) between 2014 and 2020. Data from JANIS included isolation rates and antimicrobial resistance for four bacterial species: , , , and . We modeled seasonal and annual trends using a generalized autoregressive conditional heteroskedasticity (GARCH) (1, 1) model, controlling for hospital size. Analyses examined seasonal and annual trends in isolation rates and resistance patterns, including methicillin-resistant (MRSA), multidrug-resistant (MDRP), and carbapenem-resistant (CRPA), among others. The isolation rate of decreased annually, with the most pronounced decline observed from the second to the fourth quarters, particularly in smaller hospitals. The isolation rates of and increased annually, with significant seasonal peaks in the third and fourth quarters. Antimicrobial resistance showed annual declines for MRSA, MDRP, and CRPA, particularly in smaller hospitals. However, resistance rates for third-generation cephalosporin-resistant and increased during the study period. This study demonstrates the distinct seasonal and annual trends in bacterial isolation and antimicrobial resistance in Japan. Smaller hospitals showed higher resistance rates, likely because of limited antimicrobial stewardship resources, underscoring the need for targeted interventions in these settings. These findings highlight the importance of monitoring seasonal patterns in bacterial infections and resistance to inform effective infection control and antimicrobial stewardship strategies.