title: Emergence of community-associated methicillin-resistant Staphylococcus aureus strains in the neonatal intensive care unit: an infection prevention and patient safety challenge.
abstract: Methicillin-resistant Staphylococcus aureus (MRSA) infections cause significant morbidity and mortality in neonatal intensive care units (NICUs). We characterized the clinical and molecular epidemiology of MRSA strains colonizing NICU patients. Nasal MRSA isolates (n = 250, from 96 NICU patients) recovered through active surveillance from 2009 to 2014 were characterized with staphylococcal cassette chromosome mec (SCCmec) typing and detection of mupA (marker of high-level mupirocin resistance) and qacA/B (marker associated with chlorhexidine resistance). Factors associated with community-associated (CA-) or healthcare-associated (HA-) MRSA were evaluated. The overall prevalence of MRSA nasal colonization was 3.9%. Of 96 neonates in our retrospective cohort, 60 (63%) were colonized with CA-MRSA strains and 35 (36%) were colonized with HA-MRSA strains. Patients colonized with HA-MRSA were more likely to develop MRSA infections than patients colonized with CA-MRSA (13/35, 37% versus 8/60, 13%; p 0.007), although the interval from colonization to infection was shorter in CA-MRSA-colonized infants (median 0 days, range -1 to 4 versus HA-MRSA-colonized infants, 7 days, -1 to 43; p 0.005). Maternal peripartum antibiotics were associated with CA-MRSA colonization (adjusted odds ratio (aOR) 8.7; 95% CI 1.7-45.0); intubation and surgical procedures were associated with HA-MRSA colonization (aOR 7.8; 95% CI 1.3-47.6 and aOR 6.0; 95% CI 1.4-24.4, respectively). Mupirocin- and chlorhexidine-resistant MRSA was isolated from four and eight patients, respectively; carriage of a mupirocin-resistant strain precluded decolonization. CA-MRSA strains are prominent in the NICU and associated with distinct risk factors. Given community reservoirs for MRSA acquisition and transmission, novel infection prevention strategies are needed.
authors.affiliation: Department of Pediatrics, Washington University School of Medicine, St Louis, MO, USA.
authors.forename: P J
authors.initials: PJ
authors.lastname: Reich
authors.affiliation: Department of Pediatrics, Washington University School of Medicine, St Louis, MO, USA.
authors.forename: M G
authors.initials: MG
authors.lastname: Boyle
authors.affiliation: Department of Pediatrics, Washington University School of Medicine, St Louis, MO, USA.
authors.forename: P G
authors.initials: PG
authors.lastname: Hogan
authors.affiliation: Department of Pediatrics, Washington University School of Medicine, St Louis, MO, USA; University of Texas Southwestern Medical Center, Dallas, TX, USA.
authors.forename: A J
authors.initials: AJ
authors.lastname: Johnson
authors.affiliation: Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Wallace
authors.affiliation: Department of Pediatrics, Washington University School of Medicine, St Louis, MO, USA.
authors.forename: A M
authors.initials: AM
authors.lastname: Elward
authors.affiliation: Department of Pediatrics, Washington University School of Medicine, St Louis, MO, USA.
authors.forename: B B
authors.initials: BB
authors.lastname: Warner
authors.affiliation: Department of Pediatrics, Washington University School of Medicine, St Louis, MO, USA; Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO, USA.
authors.forename: C-A D
authors.initials: CA
authors.lastname: Burnham
authors.affiliation: Department of Pediatrics, Washington University School of Medicine, St Louis, MO, USA. Electronic address: Fritz_S@kids.wustl.edu.
authors.forename: S A
authors.initials: SA
authors.lastname: Fritz
mesh_terms: D000890:Anti-Infective Agents / Q000008:administration & dosage / Q000494:pharmacology; D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology / Q000517:prevention & control; D002710:Chlorhexidine / Q000008:administration & dosage / Q000494:pharmacology; D018562:Disease Transmission, Infectious / Q000517:prevention & control; D024881:Drug Resistance, Bacterial; D005260:Female; D005838:Genotype; D006801:Humans; D007231:Infant, Newborn; D017053:Infection Control / Q000379:methods*; D007363:Intensive Care Units, Neonatal; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D058889:Molecular Typing; D016712:Mupirocin / Q000008:administration & dosage / Q000494:pharmacology; D009297:Nasal Mucosa / Q000382:microbiology*; D061214:Patient Safety; D015995:Prevalence; D012189:Retrospective Studies; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology / Q000517:prevention & control
chemical_list: D000890:Anti-Infective Agents; D016712:Mupirocin; D002710:Chlorhexidine
keywords: Chlorhexidine; Epidemiology; Infection prevention; Methicillin-resistant Staphylococcus aureus; Mupirocin; Nasal colonization; Neonatal intensive care unit; Staphylococcal cassette chromosome mec