Serratia marcescens transmission in a pediatric intensive care unit:: A multifactorial occurrence

Background: Fourteen patients in the pediatric cardiac intensive care unit (CICU) had greater than or equal to1 positive culture for a single strain of Serratia marcescens from April through December 1995 (study period). Objectives: To identify risk factors for S marcescens infection or colonization in a pediatric CICU. Methods: Retrospective case-control study. Assessment of CICU infection control practices and patient exposure to CICU health care workers (HCWs). Epidemiologic-directed cultures of the environment and HCWs' hands were obtained. Setting: Pediatric CICU. Patients: Fourteen patients in the pediatric CICU had greater than or equal to1 positive culture for a single strain of S marcescens from April through December 1995 (study period). CICU patients who did not have S marcescens infection or colonization during the study period were randomly selected as controls. Results: A case patient was more likely than a noncase patient to have exposure to a single HCW (odds ratio [OR]. 19.5; 95% CI, 2.6-416: P <.003); however, this association was not adequately explained by epidemiologic or microbiologic studies. Interviews suggested that during the outbreak period, handwashing frequency among HCWs might have been reduced because of severe hand dermatitis. Conclusions: A combination of factors, including breaks in aseptic technique. reduced frequency of handwashing among HCWs before and between caring for patients, decreased attention to infection control practices, and environmental contamination may have indirectly contributed to this S marcescens infections outbreak.