Management and investigation of a Serratia marcescens outbreak in a neonatal unit in Switzerland – the role of hand hygiene and whole genome sequencing

Gesuele Renzi,Isabelle Soulake,Jacques Schrenzel,Riccardo Pfister,Walter Zingg,Didier Pittet,Benedikt Huttner,Damien Baud,Patrice Francois

doi:10.1186/s13756-017-0285-x

Gesuele Renzi, Isabelle Soulake + Show 7 more

Open Access

https://doi.org/10.1186/s13756-017-0285-x

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Abstract

BackgroundMany outbreaks due to Serratia marcescens among neonates have been described in the literature but little is known about the role of whole genome sequencing in outbreak analysis and management.MethodsBetween February and March 2013, 2 neonates and 2 infants previously hospitalised in the neonatal unit of a tertiary care centre in Switzerland, were found to be colonised with S. marcescens. An investigation was launched with extensive environmental sampling and neonatal screening in four consecutive point prevalence surveys between April and May 2013. All identified isolates were first investigated by fingerprinting and later by whole genome sequencing. Audits of best practices were performed and a hand hygiene promotion programme was implemented.ResultsTwenty neonates were colonised with S. marcescens. No invasive infection due to S. marcescens occurred. All 231 environmental samples were negative. Hand hygiene compliance improved from 51% in April 2013 to 79% in May 2013 and remained high thereafter. No S. marcescens was identified in point prevalence surveys in June and October 2013. All strains were identical in the fingerprinting analysis and closely related according to whole genome sequencing.ConclusionsImproving best practices and particularly hand hygiene proved effective in terminating the outbreak. Whole genome sequencing is a helpful tool for genotyping because it allows both sufficient discrimination of strains and comparison to other outbreaks through the use of an emerging international database.

Highlights

Many outbreaks due to Serratia marcescens among neonates have been described in the literature but little is known about the role of whole genome sequencing in outbreak analysis and management
It is the third most common pathogen identified in published Neonatal intensive care unit (NICU) outbreaks [1], and it has been found to account for 15% of all culture-positive
At the time of the outbreak it offered 17 places in the NICU, and 12 places in the geographically separate pediatric intensive care unit (PICU), where neonates are cared for when mechanical ventilation is needed

Summary

Introduction

Many outbreaks due to Serratia marcescens among neonates have been described in the literature but little is known about the role of whole genome sequencing in outbreak analysis and management. Serratia marcescens has long been recognized as an important pathogen in neonatal intensive care units (NICUs) It is the third most common pathogen identified in published NICU outbreaks [1], and it has been found to account for 15% of all culture-positive. Zingg et al Antimicrobial Resistance and Infection Control (2017) 6:125 immaturity, prolonged hospital stay, antibiotic use, and mechanical ventilation [4, 6]. The objective of this outbreak report was to summarize the investigation and successful management of a S. marcescens outbreak in neonates and to investigate the contribution of using whole genome sequencing. This report follows the ORION (Outbreak Reports and Intervention Studies Of Nosocomial infection) statement [7]

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