Prevalence of Large Academic Research Institutions and NCI Designated Cancer Centers with Corynebacterium bovis Infections among Immunodeficient Mice in the United States from 2015 to 2023

Corynebacterium bovis is an opportunistic bacterium that infects the skin of immunodeficient mice used in biomedical research. C. bovis was first deemed clinically significant in the mid-1990s. To date, only limited data are available on the prevalence of this infection among research institutions in the United States. Here we define prevalence as the proportion of institutions that have C. bovis-infected mice in their care. To determine the national prevalence of C. bovis infections, we performed a survey of animal resource program directors and veterinarians at the NIH top 50 funded academic institutions and all Designated Cancer Centers of the National Cancer Institute. This survey was initially performed in 2015 and then expanded and repeated in 2023. Survey questions assessed institutional C. bovis status (positive, negative, or unsure), surveillance practices, and attempts to establish C. bovis-free colonies through bioexclusion. Responses were obtained from 81 institutions in 2015 and 85 in 2023, achieving 100% participation in both years. Between 2015 and 2023, C. bovis-positive status declined slightly (49% to 45%), negative responses dropped more sharply (38% to 22%), and uncertainty increased (12% to 33%), resulting in an overall shift in response distribution (P = 0.002). Despite the increased uncertainty, 69% (59/85) of all institutions in 2023 performed active surveillance for C. bovis in some form. Similarly, of institutions that self-report as having C. bovis-infected mice, 84.2% (32/38) performed C. bovis surveillance, and 78.9% (30/38) have used bioexclusion techniques. Overall, 71.7% (61/85) of institutions recognize C. bovis as an actionable pathogen. Conversely, between 20% and 28% (17 and 24/85) of institutions in 2023 did not see C. bovis as an actionable pathogen and, if present, chose to tolerate it.