Abstract

ROMANO-MAZZOTTI, Luis et al. Nosocomial bacteremia and gastrointestinal tract colonization outbreak of Serratia marcescens in Neonatal Intensive Care Unit. Bol. Med. Hosp. Infant. Mex. [online]. 2007, vol.64, n.1, pp.9-17. ISSN 1665-1146.

Introduction. We investigated an outbreak of Serratia marcescens bloodstream infection (BSI)/colonization in patients from a Neonatal Intensive Care Unit (NICU) in a tertiary care pediatric Hospital. Material and methods. May 17 through June 17, 2006 was considered as the study period. A case was defined as any patient with S. marcescens-positive culture in the NICU during the outbreak period because no S. marcescens was identified in this area within 6 month of pre-epidemic period. To identify risk factors we compared patients with S. marcescens positive-cultures with controls exposed to the cases during the outbreak period without positive cultures. Genotyping of all S. marcescens isolates were evaluated by restriction endonuclease and pulsed-field gel electrophoresis (PFGE). Results. Seven S. marcescens positive cultures were identified; the index case had a positive blood culture with diagnosis of BSI, followed by a patient with CSF positive culture with diagnosis of ventriculitis and BSI. The remaining 5 cases had concurrent S. marcescens isolates from stool cultures (colonization). Environmental cultures (water, IV solutions and inanimate surfaces) were negative for these bacteria. According to univariate analysis, patients with S. marcescens stayed in the NICU longer than controls (52 vs 27.9 days, P < 0.05), they were more likely to have an orogastric tube in place and to receive enteral nutrition. All the S. marcescens had an identical pattern of PFGE analysis. Contact precaution, including hand washing, was reinforced in addition to temporary closing of the NICU in order to control the outbreak. Conclusions. This outbreak of S. marcescens was studied using epidemiological analysis and molecular biology techniques, confirming cross-transmission between cases associated to a possible gastrointestinal reservoir. Our findings underscore the importance of hand hygiene and other contact precaution methods in hospital settings, such as NICU.

Keywords : Serratia marcescens; nosocomial outbreak; neonatal infection.

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