589. Impact of Parents and the Environment on MRSA Transmission in the Neonatal ICU

Abstract

BackgroundMethicillin-resistant Staphylococcus aureus (MRSA) colonization predisposes Neonatal Intensive Care Unit (NICU) infants to subsequent infection. Reservoirs for acquisition remain poorly understood, limiting infection prevention efforts to prevent transmission.MethodsInfants with known MRSA nasal colonization based on hospital surveillance and controls with negative MRSA screening cultures, and their parents, were enrolled in a prospective cohort study. Weekly cultures were collected from infants (4 sites), parents (3 sites), and NICU environmental surfaces (5 sites). Factors associated with MRSA colonization and infection were identified using generalized linear mixed modeling. Whole-genome sequencing (WGS) and pairwise comparisons were performed across entire genomes on 1041 S. aureus isolates using kSNP3. Isolates differing by less than 80 single nucleotide polymorphisms were considered highly related; highly related strains from different sources suggested transmission.ResultsSamples were collected 1–28 (median 7) times from 29 MRSA-colonized infants, 29 controls, 49 mothers, and 21 fathers. Over the study period MRSA colonization was detected in 10 (34%) infants who were not known to be MRSA-colonized based on hospital nasal surveillance cultures. Parent MRSA colonization (OR=11.0; 95% CI: 2.2, 55.0) and environmental MRSA contamination (OR=5.0; 95% CI: 1.6, 15.3) were associated with infant MRSA colonization. Specifically, 87% of infants with an MRSA-colonized parent were MRSA-colonized. MRSA infections occurred in 6 (21%) MRSA-colonized infants and 0 controls (P = 0.05). Infant rectal colonization (OR=15.0; 95% CI 1.6, 140.5) and persistent MRSA colonization (i.e., 3 or more consecutive positive MRSA cultures) (OR=8.4; 95% CI 1.3, 52.5) were associated with MRSA infection. Thirty clusters of highly related isolates were detected, including 12 clusters with highly related isolates from multiple study families (2–6 [median 3] unique families per cluster; Figures 1 and 2).ConclusionOur findings suggest MRSA transmission between infants, their parents, and the environment as well as transmission between patients. Future infection prevention efforts should consider parent and environmental reservoirs, as well as the role of extranasal sites of colonization. Disclosures All authors: No reported disclosures.