RESUMEN
Serratia marcescens has been reported as an organism which can cause rapidly spreading, antibiotic resistant nosocomial colonization and disease. We report here an outbreak of colonization and disease due to S. marcescens involving 53 infants admitted to the Neonatal Intensive Care Unit (NICU) of the Uberlândia Federal University Hospital, Brazil, between December, 1997, and April, 1998. Thirty-eight infants were colonized without clinical signs of infection and 15 infants had clinical disease. Five infants developed septicemia (4 cases were fatal, including the presumed index case). Seven infants developed conjunctivitis, 1 developed both sepis and conjunctivitis, 1 infant developed otitis, and 1 infant had a urinary tract infection. On univariate analysis, independent risk factors for S. marcescens clinical disease were: low birth weight (<1.500g), incubator care, use carbapenems, duration of hospitalization (maior igual que 7 days), low Apgar score, and prematurity. All the isolates of S. marcescens showed the same antimicrobial susceptibility profile. The causative strains were resistant to oxyimino-cephalosporins due to their production of extended-spectrum ß-lactamases. Cultures from the hands of the NICU health care professionals (HCWs), soap samples, ventilator reservoirs, and work and incubator surfaces failed to identify a reservoir of S. marcescens, but positive cultures were found in half of the sink drains. Containment of the outbreak was achieved by closure of the NICU new admissions, employment of strict hygienic measures, and careful nursing care of the infected and colonized infants. Rapid organism identification and initiation of control measures are important in containing such an epidemic at an early stage.