Rapid Control of Two Outbreaks of Serratia marcescens in a Northern Italian Neonatal Intensive Care Unit

Molecular Characterization by Whole-Genome Sequencing of Clinical and Environmental Serratia marcescens Strains Isolated during an Outbreak in a Neonatal Intensive Care Unit (NICU)

The whole-genome sequencing (WGS) of eighteen S. marcescens clinical strains isolated from 18 newborns hospitalized in the Neonatal Intensive Care Unit (NICU) at Pescara Public Hospital, Italy, was compared with that of S. marcescens isolated from cradles surfaces in the same ward. The identical antibiotic resistance genes (ARGs) and virulence factors were found in both clinical and environmental S. marcescens strains. The aac(6′)-Ic, tetA(41), bla_SRT-3, adeFGH, rsmA, and PBP3 (D350N) genes were identified in all strains. The SRT-3 enzyme, which exhibited 10 amino acid substitutions with respect to SST-1, the constitutive AmpC β-lactamase in S. marcescens, was partially purified and tested against some β-lactams. It showed a good activity against cefazolin. Both clinical and environmental S. marcescens strains exhibited susceptibility to all antibiotics tested, with the exception of amoxicillin/clavulanate.

An Outbreak of Serratia marcescens in a Moroccan Neonatal Intensive Care Unit

Serratia marcescens (S. marcescens) is an Enterobacteriaceae microorganism that is widespread in the environment, which may be the source of nosocomial infections, rare in the newborn but severe, and often in the form of outbreaks. The aim of our study is to report our experience, during an outbreak of S. marcescens, to show the severity of this germ, with review of the literature. Our study was retrospective, including 8 newborns with S. marcescens nosocomial infection, collected in the neonatal intensive care unit of Mohammed VI University Medical Hospital, during the epidemic period, over a period of 2 months (July and August 2016). The mean gestational age of the cases was 36 weeks of amenorrhea. Boys accounted for 75% of the cases. The average weight was 1853 grams. All the patients were initially placed under empiric antibiotic therapy based on ceftriaxone and gentamicin. The mean duration of nosocomial infection, diagnosed in all cases by blood cultures, was 7 days. The strains of S. marcescens were in 75% of the cases sensitive to the cephalosporins, intermediate sensitivity in 12.5% of cases and resistant in 12.5% of cases. The outcome was fatal in 62.5% of cases. S. marcescens nosocomial infections are often reported on epidemic series, and their eradication is not always easy.

Serratia marcescens infections and outbreaks in neonatal intensive care units

Serratia marcescens is an important cause of hospital-acquired infections, especially in neonatal intensive care units (NICUs). This review analyzes clinical signs, risk factors, biotyping and sources of infection in newborns exhibited by this bacteria as well as the therapy which is commonly used and management. This review examines the reported cases of outbreaks of S. marcescens in NICUs published in pubmed over the last 10 years (key words: Serratia marcescens infections, outbreaks, Neonatal intensive Care Units). This report highlights the different prevention and control strategies employed in order to eradicate Serratia outbreaks in NICUs, including all healthcare procedures such as hand washing, introduction of alcohol-based antiseptic gel, enhanced cleaning and disinfection of medical equipment and wards, use of single-patient medical instruments, cohorting of colonized and infected infants, periodic screening cultures, earliest discharge of the infants.