Nosocomial Urinary Tract Infection with Serratia marcescens: An Epidemiologic Study

Abstract

Frequent nosocomial urinary tract infection (>10⁵ organisms/ ml) with nonpigmented Serratia marcescens was found in patients on the urology ward of a large Veterans Hospital. Serotyping and antibiograms suggested a single endemic strain. Each of 10 patients who became infected in a 27-day prospective study had an indwelling Foley catheter (P < .001) and was receiving one or more antimicrobial agents at the time of infection. Negligible rectal or pharyngeal carriage of Serratia was demonstrated among either patients or hospital personnel, and few environmental sources of Serratia were identified; however, the organism was isolated from the pooled hand rinsings of hospital personnel on four of eight occasions. A catheterized patient's risk of infection was significantly greater (62 % vs. 17%, P = .029) if an infected catheterized patient shared the same hospital room. These data suggest that, on this urology ward, S. marcescens is transmitted between catheterized patients by passive carriage on the hands of noncolonized hospital personnel. Heavy usage of antibiotics very probably promotes the selection of Serratia and the predominance of highly resistant strains.