International Journal of Hygiene and Environmental Health
Outbreaks of Serratia marcescens in neonatal and pediatric intensive care units: Clinical aspects, risk factors and management
Introduction
Serratia marcescens, a Gram-negative bacterium, has been described as an important opportunistic pathogen in neonatal (NICI) and pediatric (PICU) intensive care units. According to the European collaborative study of Raymond et al. (Raymond and Aujard, 2000), S. marcescens accounted for 5% and 15% of all culture-positive nosocomial infections in PICUs and in NICUs, respectively. In a case control study from an Italian PICU (Foglia et al., 2007), S. marcescens was the causative pathogen in 8% of all bacterial nosocomial infections. S. marcescens has been identified as the responsible pathogen in 11% (Larson et al., 2005) and 16% (Graham et al., 2006) of all Gram-negative bloodstream infections (BSIs) in US-American NICUs. Since the organism is capable of surviving on the hands of healthcare workers (HCWs) (Milisavljevic et al., 2004) transient hand carriage is thought to foster nosocomial transmission.
In a case control study recently published by Al Jarousha et al. (Al Jarousha et al., 2008), S. marcescens was detected in blood cultures of 159 confirmed nosocomial BSIs. Seventy (44%) of these neonates died due to S. marcescens infection and 89 recovered. This study compared patients with S. marcescens sepsis with uninfected controls. Risk factors significantly associated with S. marcescens infection in multivariate analysis were birth weight <1,500 g (OR, 1.7; P=0.026); <37 weeks gestational age (OR, 2.0; P=0.002); and use of mechanical ventilation (OR, 2.3; P=0.001). The potentially devastating sequelae of late onset S. marcescens infections in preterm infants have been confirmed in a case series of Berger et al. (Berger et al., 2002) who reported five cases of septicemia with S. marcescens in neonates during a nosocomial outbreak (Assadian et al., 2002). Three of five patients developed meningitis with multiple brain abscesses. Mild clinical and laboratory findings of infection contrasted with excessive tissue destruction determined on MRI scans (Berger et al., 2002). Anderson et al. (Anderson et al., 2008) described a significantly higher infection rate in NICU patients colonized with S. marcescens (1:6; 17%) compared with infants colonized with Enterobacter cloacae (1:41; 2.4%), Enterobacter aerogenes (1:11; 9%), or Klebsiella pneumoniae (1:27; 3.7%).
The aim of this review is to describe important characteristics of S. marcescens outbreaks in neonatal and pediatric intensive care units. Hitherto, several nosocomial outbreaks of S. marcescens have been published, but no systematic analysis is available. The conclusions for clinical practice derived from this analysis are presented to support clinical decision making by the attending physicians, pediatric infectious disease specialists and hospital infection control teams in case of a S. marcescens outbreak in the NICU or PICU setting.
Section snippets
Materials and methods
The PUBMED database was utilized to search for publications with “Serratia marcescens” and “outbreak” as keywords, plus additional terms including “neonates”, “pediatric patients”, and “nosocomial infection”. In addition, the outbreak database, a web-based register for nosocomial outbreaks (http://www.outbreak-database.com/) was used to complete the literature search (Gastmeier et al., 2004). Citations were selected from articles published in English.
Studies were only included in the analysis
Basic data and infection rates (Table 1)
In total, 27 studies reporting on 34 outbreaks of S. marcescens were included in the analysis. The vast majority (93%) of reported outbreaks were from the NICU setting, one from a PICU (Cimolai et al., 1997), and one from a pediatric cardiac surgical intensive care unit (PCICU) (Manning et al., 2001); in two publications, the outbreak extended from the NICU to the PICU in the same hospital (Miranda et al., 1996; Steppberger et al., 2002). In total, 575 patients were involved.
Types of infection
The most prevalent
Conclusions
The different strategies of intervention to contain outbreaks of S. marcescens in the setting of neonatal or pediatric intensive care units have not been investigated in prospective randomized studies. Nonetheless, the available literature analyzed in this study demonstrates that nosocomial transmission of S. marcescens in outbreak settings can be successfully interrupted. From the perspective of the authors the points addressed in Table 4 should be considered by the outbreak management team.
Conflict of interest
None of the authors declares a conflict of interest.
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