title: Molecular Epidemiology of a Vancomycin-Intermediate Heteroresistant Staphylococcus epidermidis Outbreak in a Neonatal Intensive Care Unit.
abstract: Coagulase-negative staphylococci (CoNS) have become the leading cause of bloodstream infections (BSIs) in intensive care units (ICUs), particularly in premature neonates. Vancomycin-intermediate heteroresistant CoNS (hVICoNS) have been identified as sources of BSIs worldwide, and their potential to emerge as significant pathogens in the neonatal ICU (NICU) remains uncertain. This study describes the molecular epidemiology of an outbreak of vancomycin-heteroresistant (hV) Staphylococcus epidermidis central-line-associated BSI (CLABSI) in a single tertiary care NICU and compares it to a second tertiary care NICU that had not been associated with an outbreak. Between November 2009 and April 2014, 119 S. epidermidis CLABSIs were identified in two tertiary care NICUs in Quebec, Canada. Decreased vancomycin susceptibility was identified in about 88% of all collected strains using Etest methods. However, discrepancies were found according to the Etest and population analysis profiling-area under the concentration-time curve (PAP-AUC) methods used. All strains were susceptible to linezolid, and a few isolates were nonsusceptible to daptomycin. Great genetic diversity was observed within the collection, with 31 pulsed-field gel electrophoresis (PFGE) patterns identified. The outbreak strains were all determined to be heteroresistant to vancomycin and were polyclonal. The study identified two major clones, PFGE patterns E and G, which were found in both NICUs across the 5-year study period. This suggests the persistence of highly successful clones that are well adapted to the hospital environment. hV S. epidermidis seems more common than currently realized in the NICU, and certain hV S. epidermidis clones can become endemic to the NICU. The reservoirs for these clones remain unknown at this time, and identification of the reservoirs is needed to better understand the impact of hV S. epidermidis in the NICU and to inform infection prevention strategies. In addition, there is a need to investigate and validate hV determination protocols for different species of CoNS.
authors.affiliation: Department of Epidemiology and Biostatistics, McGill University, Montreal, QC, Canada.
authors.forename: Jasmine
authors.initials: J
authors.lastname: Chong
authors.affiliation: Department of Epidemiology and Biostatistics, McGill University, Montreal, QC, Canada Infectious Disease Division, Department of Pediatrics and Department of Medical Microbiology, Montreal Children's Hospital of the McGill University Health Centre, Montreal, QC, Canada.
authors.forename: Caroline
authors.initials: C
authors.lastname: Quach
authors.affiliation: Infectious Disease Division, Department of Pediatrics and Department of Medical Microbiology, Montreal Children's Hospital of the McGill University Health Centre, Montreal, QC, Canada Department of Pediatrics, CHU Sainte Justine, University of Montreal, QC, Canada.
authors.forename: Ana C
authors.initials: AC
authors.lastname: Blanchard
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada Department of Pediatrics and Child Health, University of Manitoba, Winnipeg, MB, Canada.
authors.forename: Philippe Guillaume
authors.initials: PG
authors.lastname: Poliquin
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada.
authors.forename: George R
authors.initials: GR
authors.lastname: Golding
authors.affiliation: Department of Pediatrics, CHU Sainte Justine, University of Montreal, QC, Canada.
authors.forename: Céline
authors.initials: C
authors.lastname: Laferrière
authors.affiliation: Laboratoire de Santé Publique du Québec, Institut National de Santé Publique du Québec, Sainte-Anne-de-Bellevue, QC, Canada simon.levesque@inspq.qc.ca.
authors.forename: Simon
authors.initials: S
authors.lastname: Lévesque
mesh_terms: D016470:Bacteremia / Q000453:epidemiology / Q000382:microbiology; D004196:Disease Outbreaks; D024881:Drug Resistance, Bacterial / Q000187:drug effects*; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal; D008297:Male; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D058885:Multilocus Sequence Typing; D011792:Quebec / Q000453:epidemiology; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology / Q000401:mortality; D013212:Staphylococcus epidermidis / Q000187:drug effects* / Q000302:isolation & purification / Q000472:pathogenicity; D014640:Vancomycin / Q000494:pharmacology*
chemical_list: D014640:Vancomycin