686. Comparing Treatments of Methicillin-Resistant Staphylococcus aureus Infective Endocarditis by People Who Inject Drugs

Abstract Background People who inject drugs (PWID) are at high risk for infective endocarditis (IE) with high-mortality pathogens such as methicillin-resistant Staphylococcus aureus (MRSA). Stigma against PWID may cause differences in treatment and outcomes between these patients infected with MRSA IE. Methods Single center retrospective cohort study from August 2006 to February 2021 that includes adult patients diagnosed with IE. Primary outcomes included 90-day all-cause mortality, 60-day MRSA recurrence, 60-day readmission, and hospital length of stay (LOS). Statistical analysis was performed by chi-square, t-test, and Mann-Whitney-U as appropriate. Results A total of 214 patients were diagnosed with MRSA IE; 89 PWID and 125 non-PWID. The mean (SD) age was 47.4±12.4 years (PWID) vs 59.3 ±16.0 years (non-PWID) (p< 0.001). Patients were primarily male (56%), but differed in terms of race 34% African-American (AA) (PWID) vs 66% AA (non-PWID) (p< 0001). Mean APACHE II scores differed between groups: 16(±9.9) (PWID) vs 19(±8.1) (non-PWID) (p< 0.008). Among patients who cleared bacteremia, mean (SD) duration was 5.7(±3.9) days and was not significant between groups (p< 0.64). Valve-type was 93% native and 7% prosthetic and not different between groups (p< 0.16). Infectious Diseases consult did not differ at 96% overall (p< 0.31), but pursuit of source control nearly reached significance at 27% for PWID vs 41% non-PWID (p< 0.06). Similarly, use of combination therapy daptomycin and ceftaroline was nearly significant: 21% (PWID) vs 12% (non-PWID) (p< 0.09). Odds ratio of PWID and combination therapy remained non-significant after regression: 0.39(0.14-1.1,p< 0.07). Primary 90-day mortality was lower in PWID vs non-PWID (15% vs 30%) respectively (p< 0.01), but did not differ in 60-day MRSA recurrence (p< 1.0) at 9%, 60-day readmission (p< 1.0) at 33%, or median LOS (IQR) (p< 0.46) at 15 (10-24) days overall. Conclusion While PWID are significantly younger, less critically ill, and have lower mortality compared to non-PWID, they have similar LOS, MRSA recurrence, and readmission rates. Analyses suggest a potential difference in the pursuit of source control and combination therapy among PWID, however more studies may be needed to achieve significance. Disclosures Michael J. Rybak, PharmD, MPH, PhD, Paratek Pharmaceuticals (Research Grant or Support)