Serratia marcescens nosocomial infections of the urinary tract associated with urine measuring containers and urinometers

An outbreak of nosocomial infections of the urinary tract due to a multiply drug-resistant strain of Serratia marcescens occurred at a community hospital. Acquisition of the epidemic strain was associated with the following factors: (1) exposure to the intensive care unit, (2) presence of an indwelling bladder catheter, (3) treatment with antibiotics, and (4) exposure to devices used from measurements of specific gravity and urine volume. An extensive microbiologic evaluation of the hospital environment failed to reveal the epidemic strain of S. marcescens from any site other than urinometers and urine volume measuring containers. Four of four urinometers and three of seven urine measuring containers tested revealed the epidemic organism. Notably, six of these seven positive cultures were obtained in hospital areas in which no patients infected with S. marcescens were located at the time of sampling. The resistant organism was also recovered from one of three pooled handwashings taken from nursing personnel. Thus, the urinometer and urine measuring container may have served as inanimate reservoirs for the resistant S. marcescens which was subsequently inoculated onto the hands of medical personnel or directly to a catheterized patient. Disinfection procedures were identified which eliminated these items as reservoirs. No additional cases of multiply drug-resistant S. marcescens urinary tract infections have been observed since institution of routine disinfection of the inanimate reservoir.