Three episodes of nosocomial urinary tract infections caused by one O-serotype of Providencia stuartii.

The results of O-serotyping Providencia stuartii isolates in a general hospital showed that 43 isolates were the same serotype (063) and were from 15 patients located in 1 or 2 adjacent wards. On retrospective examination it was found that the series of infections occurred during a 9-month period and could be separated into 3 episodes, involving 7, 6 and 2 patients. All patients who acquired the Providencia stuartii 063 strain were catheterized. The introduction of the strain into the hospital was attributed to a patient catheterized before admission from an institution in which the 063 strain had been identified previously. Antibiotic irrigation was not successful in eliminating Providencia stuartii from the urine and the procedure may be a predisposing factor in preferentially selecting strains of this species.