1247. Genomic Epidemiology of MRSA DURING Incarceration at a Large Inner-City Jail

BACKGROUND: Congregate settings may facilitate spread of USA300. Jails may be a location where individuals already colonized with MRSA (from preceding exposures) intermingle with others, potentially augmenting spread. We examined the rate of MRSA acquisition during incarceration and characterized the genomic epidemiology of MRSA strains entering the jail, MRSA acquisition isolates, and archived (2015–2017) clinical MRSA isolates from male detainees. METHODS: Males incarcerated at the Cook County Jail were enrolled within 72 hours of intake and surveillance cultures for MRSA carriage (nares, throat, groin) collected. Detainees in jail at Day 30 had cultures repeated to determine MRSA acquisition. A survey was administered and chart review performed to identify predictors of acquisition. Whole-genome sequencing and phylogenetic analysis of isolates were performed with integration of epidemiologic data. RESULTS: 800 males were enrolled, with 19% colonized with MRSA at jail intake. 143 reached the Day30 visit (82% AA, 7% Hispanic), by which there were 12 MRSA acquisitions detected. Heroin use before entering the jail (OR 3.67, P = 0.04) and sharing personal items during incarceration (OR = 4.92, P = .01) were significant predictors of acquisition. Sequenced clinical isolates (n = 175) (largely skin infections) were more likely to resemble each other genetically than the diverse intake strains (P < 0.001) (figure), suggesting clinical isolates may originate from transmission within the jail or be due to more virulent strains. 7/12 (58%) acquisition isolates were within 40 SNVs from another isolate; five were genomically similar to intake isolates and two were similar to clinical isolates. Acquisition strains from those sharing personal items (vs. not) tended to have closer relatedness (19 SNVs vs. 56 SNVs, P = 0.22). CONCLUSION: There is a high burden of MRSA entering jail. Genomic analysis of acquisition and clinical isolates suggests potential spread of incoming strains and possible networks spread of prevalent strains during incarceration. Sharing of personal items during incarceration is associated with MRSA acquisition and could be a focus of an intervention. Future study of epidemiologic and location data may inform targeting of interventions within the jail. [Image: see text] DISCLOSURES: All authors: No reported disclosures.