Regional Prevalence of Carbapenemase-Producing Enterobacterales and Extended-Spectrum Beta-Lactamase-Producing Enterobacterales in Okayama and Neighboring Prefectures, Japan.

Carbapenemase-producing Enterobacterales (CPE) and extended-spectrum β-lactamase (ESBL)-producing Enterobacterales (ESBL-E) are representative antimicrobial-resistant pathogens. We investigated the prevalence of CPE and ESBL-E in Okayama, Japan to clarify their current epidemiology and potential clinical burden. Active surveillance for CPE and ESBL-E was performed first, using stool samples submitted to the Okayama Medical Laboratory (Japan) in the years 2024-2025. Screening was performed using a selective agar (CHROMagar mSuper CARBA/ESBL). Phenotypic identification was conducted with the use of a modified carbapenem inactivation method and double-disk phenotypic confirmatory tests. Clinical information including patient age, sex, sampling date, and hospital address were collected, and the data were analyzed according to specimen origin (hospitals, clinics, and health checkups). A total of 2,000 stool samples were screened, of which two CPE isolates (0.1%) and 285 ESBL-E isolates (14.3%) were identified. By specimen origin, the ESBL-E positivity rate was significantly higher in hospitals (17.4%) than in clinics (11.8%). By age category, the late elderly (> 75 years) exhibited the highest ESBL-E positivity rate (22.6%) compared to other age groups. In the clinics and health checkups, infants (0 years) demonstrated high ESBL-E positivity rates (18.2% and 14.3%, respectively). Escherichia coli was the most common ESBL-E organism in the hospitals (77.2%), clinics (88.8%), and health checkups (87.5%). Our active screening demonstrated that the prevalences of CPE and ESBL-E were within the reported ranges; however, in this era of increasing internationalization, continuous surveillance of these notifiable pathogens is warranted.