The long-term-catheterized urinary tract may offer a particular niche to Providencia stuartii, which is otherwise an uncommon clinical isolate. Published accounts of bacteriuria in patients catheterized for long periods indicate that P. stuartii has often been found as frequently as familiar uropathogens such as Escherichia coli, Proteus mirabilis, enterococcus, and Pseudomonas aeruginosa. As in most nosocomial infections, the frequency of isolation of a given species has commonly differed among institutions. In the future P. stuartii may be more frequently encountered as a nosocomial pathogen in nursing homes and in acute care hospitals to which bacteriuric patients are transferred. This trend appears likely because of the increasingly large nursing-home population, the predilection of the bacterium for the long-term-catheterized urinary tract, the opportunity for nosocomial transmission from this reservoir, the resistance of the organism to multiple antibiotics, and the occasional systemic illness and bacteremia caused by P. stuartii.