1025. Microbial Epidemiology of Infectious Endocarditis in the Intravenous Drug Abuse Population: A Retrospective Study in East Tennessee

Background Infective endocarditis (IE) is one of the most serious infections affecting intravenous drug users (IVDU). IVDU have a higher incidence of IE compared with the general population. There are a limited number of reports on the epidemiology of this infection from the South Eastern United States. We determined the prevalence, and the microbial epidemiology, of IE cases at our institution. We then compared this to data from other geographical regions. This was done to help aid physicians with choosing empiric treatment regimens, for IE, pending culture results. Methods A retrospective cohort of 299 cases of IE was analyzed between January 2013 and July 2017 at a university hospital in East Tennessee. Demographic, microbiologic, intravenous substance use status, radiographic, and echocardiographic data were collected. Results Of the 299 cases, 184 (61.5%) were IVDU and 115 cases (38.5%) were non-IVDU. IVDU and non-IVDU positive cultures rates were similar at 87% and 86%, respectively. Methicillin-resistant Staphylococcus aureus (MRSA) was more likely to occur in IVDU (OR 2.8, P < 0.001) and was the most common pathogen at 77 out of the 184 cases (42%). Twenty-three of the 115 (20%) cases grew MRSA in the non-IVDU population. Methicillin-sensitive Staphylococcus aureus was the second most common bacteria for IVDU with 36 out of 184 cases (19.6%). IVDU patients were more likely infected with Pseudomonas aeruginosa (OR 3.384, P = 0.027), which occurred in 20 of the 184 cases (10.9%). IVDUs also experienced more right heart involvement vs. left sided involvement (OR 2.19, P = 0.004). Conclusion S. aureus was the most common pathogen for IE in IVDU followed by P. aeruginosa. Data from this study solidify that in IVDU, or if there is suspicion of intravenous drug use, first-line broad-spectrum antibiotics with excellent MRSA and P. aeruginosa coverage is essential to empirically cover for IE. Extra attention for right-sided heart involvement should also be made on IVDU with imaging modalities. Disclosures All authors: No reported disclosures.