Clinical, epidemiologic and microbiologic features of a persistent outbreak of amikacin-resistant Serratia marcescens.

This article describes a prolonged outbreak (January 1977 to February 1980) of amikacin-resistant Serratia marcescens (ARSM) urinary infections and the methods used for its control. Significant factors predisposing to ARSM urinary tract infection included an extended hospital stay, being in the urology ward, and undergoing urologic surgery. There had been on prior administration of amikacin or of other aminoglycosides in 20 of 27 patients with ARSM urinary tract infections. Chronically infected patients who required multiple hospitalizations represented a major reservoir for the perpetuation of the outbreak, overshadowing the importance of aminoglycoside use. Traditional control measures and even a major change in the inanimate environment were only partially effective in controlling the outbreak, but treatment of bacteriuric patients in the urology unit with "second and third generation" cephalosporins interrupted patient-to-patient transmission. No new cases of ARSM bacteriuria appeared in the urology unit in the ensuing 12 months.