Regional and temporal genotype profiling of Clostridioides difficile in a multi-institutional study in Japan.

Clostridioides difficile, a cause of healthcare-associated infections, poses a significant global health threat. This multi-institutional retrospective study focuses on epidemic dynamics, emphasizing minor and toxin-negative clinical isolates through high-resolution genotyping. The genotype of the C. difficile clinical isolates during 2005 to 2022 was gathered from 14 hospitals across Japan (N = 982). The total number of unique genotypes was 294. Some genotypes were identified in every hospital (cross-regional genotypes), while others were unique to a specific hospital or those in close geographic proximity (region-specific genotypes). Notably, a hospital located in a sparsely populated prefecture exhibited the highest prevalence of region-specific genotypes. The isolation rate of cross-regional genotypes positively correlated with the human mobility flow. A 6-month interval analysis at a university hospital from 2019 to 2021 revealed a temporal transition of the genotype dominance. The frequent isolation of identical genotypes over a brief timeframe did not always align with the current criteria for defining nosocomial outbreaks. This study highlights the presence of diverse indigenous C. difficile strains in regional environments. The cross-regional strains may have a higher competency to spread in the human community. The longitudinal analysis underscores the need for further investigation into potential nosocomial spread.