Population-based study of Morganella-Proteus-Providencia group bloodstream infections

Background: There is a paucity of studies investigating the population-based epidemiology of Morganella-Proteus-Providencia (MPP) group infections. Our objective was to determine the incidence, risk factors, and outcome of MPP group bloodstream infections (BSI), and explore species-specific differences. Methods: Population-based surveillance was conducted in the western interior of British Columbia, Canada, between April 1, 2010 and March 30, 2020. Results: Sixty-two incident MPP group BSI occurred for an annual incidence of 3.4 per 100,000 residents; rates for Morganella morganii, Proteus mirabilis, and Providencia species were 0.5, 2.6, and 0.3 per 100,000 population, respectively. The median year of age was 72.5 and was different ( p = 0.03) among the groups. Most (92%) MPP group BSIs were of community-onset. Significant differences were observed in the distribution of clinical focus of infection, with most notably 81% of P. mirabilis BSI due to genitourinary focus as compared to 60% and 22% for Providencia species and M. morganii, respectively. Comorbid illnesses that increased the risk for development of MPP group BSI (incidence rate ratio; 95% CI) were HIV infection (37.0; 4.4–139.6), dementia (11.5; 6.1–20.7), cancer (6.4; 3.2–11.9), stroke 6.5 (2.8–13.3), and diabetes 2.7 (1.3–5.0). Thirteen, one, and none of the cases with P. mirabilis, M. morganii, and Providencia species BSI died within 30 days of index culture for respective all cause case-fatalities of 27%, 11%, and 0% ( p = 0.1). Conclusions: Although collectively responsible for a substantial burden of illness, the epidemiology of MPP group BSI varies significantly by species.