Late-onset neonatal sepsis, risk factors and interventions: an analysis of recurrent outbreaks of Serratia marcescens, 2006-2011

Background: Between 2006 and 2011, 11 patients with Serratia marcescens sepsis and 47 patients colonized due to the spread of various clones were observed. These recurrent clusters brought about interventions to reduce spread between patients. Aim: To evaluate the effect of stepwise interventions to prevent S. marcescens colonization/sepsis and to analyse risk factors for late-onset sepsis (LOS). Methods: An open retrospective observational study was performed to evaluate the interventions. A retrospective case-control study was performed to analyse the risk factors for LOS. Findings: S. marcescens sepsis and colonization decreased after the stepwise adoption of hygiene interventions. Low gestational age, low birth weight, indwelling central venous or umbilical catheter, and ventilator treatment were identified as risk factors for LOS. Compliance with basic hygiene guidelines was the only intervention monitored continuously from late 2007. Compliance increased gradually to a steady high level in early 2009. There was a decrease in S. marcescens LOS, clustering after the second quarter of 2008. After the first quarter of 2009, S. marcescens colonization decreased. Conclusion: It was not possible to identify the specific effects of each intervention, but it is likely that an update of the hospital's antibiotic policy affected the occurrence of S. marcescens LOS. The delayed effect of interventions on S. marcescens colonization was probably due to the time it takes for new routines to have an effect, illustrated by the gradual increase in compliance with basic hygiene guidelines. (C) 2013 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.