469. Contributions of Infections among Persons Who Inject Drugs to the Changing Incidence of Healthcare-Associated, Community-Onset Methicillin-Resistant Staphylococcus aureus Infections, 2009–2017

BACKGROUND: Recently, overall reductions for invasive MRSA infections (isolation from a normally sterile site) have slowed. Healthcare-associated community-onset (HACO) invasive methicillin-resistant Staphylococcus aureus (MRSA) infections are those with recent healthcare exposures who develop MRSA infection outside acute care hospitals, and account for most invasive MRSA infections. HACO incidence decreased 6.6% per year during 2005–2008; the contribution of persons who inject drugs (PWID) to HACO incidence has not been reported. METHODS: We identified invasive MRSA infections using active, population- and laboratory-based surveillance data during 2009–2017 from 25 counties in 7 sites (CA, CT, GA, MD, MN, NY, TN). Cases were HACO if culture was obtained from an outpatient, or ≤3 days after hospitalization in a patient with ≥1 of the following healthcare exposures (HEs): hospitalization, surgery, dialysis, or residence in a long-term care facility (LTCF) in the past year; or central vascular catheter ≤2 days before culture. We calculated incidence (per census population) overall, for PWID cases and others, and for cases associated with each HE. For each HE, we calculated the proportion of overall incidence increase for PWID and others. RESULTS: HACO MRSA incidence declined overall from 2009 to 2016 but increased from 2016 to 2017 overall (8%), for both PWID (63%) and others (5%) (figure). For both PWID and non-PWID, incidence from 2016 to 2017 increased by 0.5 cases/100,000 population; 91% of the increase in PWID occurred in cases with a past year hospitalization while 78% of the increase in cases not associated with injection drug use (IDU) occurred in cases with past year LTCF residence. Past year LTCF residence was less common among PWID (16%) then among other cases (38%, P < 0.01). CONCLUSION: After years of declines, HACO MRSA incidence increased equally in 2017 for cases associated with IDU and in cases unrelated to IDU. Increases in PWID-associated cases account for half the overall increase, indicating that efforts to reduce HACO MRSA should address PWID risk factors as these infections may be due to self-injection. In addition, increases not related to PWID, if sustained, would be a reversal of historic trends and require further investigation into causes. [Image: see text] DISCLOSURES: All authors: No reported disclosures.