Differentiation of Providencia species bloodstream infections: A population-based analysis

Background: Although Providencia species are recognised as important causes of bloodstream infections (BSI), their epidemiology is not well defined due to their infrequent occurrence. Our objective was to determine the overall incidence, determinants, and outcomes of Providencia species BSI, and compare the epidemiology of P. stuartii and P. rettgeri in a large population.

Methods: All patients within Queensland, Australia with Providencia species BSI between 2000-2019 were included with clinical and outcome data collected from state-wide datasets.

Results: Among 268 residents, there was 273 incident episodes of Providencia species BSI; with 118 cases (43.2%) due to P. rettgeri, 150 cases (55.0%) due to P. stuartii, for age and sex adjusted incidence rates of 1.5, and 2.1 per million respectively. Five cases (<2.0%) were due to other Providencia species. The median age was 73.9 years, 80% were male, and most episodes were of community onset. As compared to P. rettgeri, patients with P. stuartii BSI were more likely to have dementia, peptic ulcer disease, and hemiplegia but less likely to have comorbid liver disease. The overall distribution of infection foci were different with P. stuartii more commonly associated with lower respiratory tract source and P. rettgeri with urinary source. All cause 30-day case fatality was significantly higher for P. rettgeri versus P. stuartii (35; 29.7% vs. 24; 16%; p=0.007).

Conclusions: Providencia species are important causes of community onset BSI especially in older males. Although they share similar incidence, P. stuartii and P. rettgeri BSI differ on many clinical aspects.