The impact of infectious diseases department on the incidence of hospital-onset bacteremia and fungemia at a tertiary care center: a retrospective cohort study

Introduction: Cases of hospital-onset bacteremia and fungemia (HOBF) are on the rise in Japanese hospitals, but little is known about their incidence in hospitals and how it relates to the availability of services provided by infectious diseases departments. Methods: We herein investigated the monthly incidence density of HOBF per 1,000 patient days from 2013 through 2023 at a tertiary care hospital in Japan. The incidence of overall HOBF and pathogen-specific HOBF, including those caused by Enterobacterales, Staphylococcus aureus, coagulase-negative staphylococci (CNS), and Candida species, was tracked. Changes in the HOBF trend before and after the establishment of an infectious diseases department at the hospital were evaluated. Results: In total, 4,315 HOBF-related events were identified. The overall incidence density of HOBF increased by 2.4-fold from 0.58 per 1,000 PD in 2013 to 1.42 per 1,000 PD in 2023. Both the level and trend changes in the incidence density of overall HOBF (+0.3142 for change in level [P <.001]; +0.0085 for change in trend [P <.001]), HOBF caused by S. aureus (+0.0983 for change in level [P <.001]; +0.0016 for change in trend [P = 0.016]), and Candida spp. (+0.0466 for change in level [P = 0.030]; +0.0019 for change in trend [P = 0.002]) significantly increased after the establishment of the infectious diseases department. Conclusion: The incidence density of overall HOBF and clinically important pathogen-specific HOBF increased over the last decade. The availability of services through the infectious diseases department was significantly associated with an increase in the HOBF incidence, likely suggesting improvement in the diagnosis of HOBF.