Nosocomial urinary tract infections caused by two O-serotypes of Providencia stuartii in one hospital.

Providencia stuartii nosocomial urinary tract infections occurring in the same hospital over an 18-month period of retrospective study were shown, by serotyping and biotyping, to have been caused by two endemic strains. Two episodes, involving 38 patients in one ward and 11 patients in another, were caused by a mannitol-positive strain of serotype O55. Transmission of the strain through the movements of one patient appeared to have been the basis for the introduction of the agent from one ward to the other. In another episode, involving two patients in a third ward, the infections were caused by a mannitol-negative strain of serotype O49. The study demonstrated the usefulness of serotyping and biotyping in epidemiological studies of infections caused by P. stuartii.