Infective Endocarditis in Intravenous Drug Users from Italy: the Increasing Importance in HIV-infected Patients

Abstract

Intravenous drug users (IDUs) are at increased risk of infective endocarditis (IE). Episodes of IE in IDUs were retrospectively analyzed in this multicenter study. Cases were collected between 1986 and 1999. Only definite diagnosis according to the Duke criteria were analyzed. Two hundred and sixty-three cases, including 100 cases in HIV-positive patients, were observed in IDUs. Any right-sided involvement was detected in 167 out of 263 cases (63.5%) and any left-sided involvement in 115 out of 263 cases (43.7%). The tricuspid valve (TV) alone was affected in 135 cases (51.3%), the mitral valve alone in 32 patients (12.1%), the aortic valve alone in 41 cases (15.6%) and the pulmonic valve alone in 3 cases. Staphylococcus aureus was isolated in 156 cases (59.3%) and Streptococcus spp. in 33 cases (12.5%). No major differences were observed between HIV-negative and HIV-positive patients. Any TV valve involvement was significantly associated with female rather than male gender (p = 0.02). There was a significant association between S. aureus etiology and TV involvement (p < 0.0001). The mortality rate was 16%. On multivariate analysis, only left-side IE (p = 0.0006; OR 5.2; 95% CI 2.0-13.5) and age greater than 35 years (p = 0.0068; OR 3.6; 95% CI 1.4-9.0) were independently associated with mortality. Infective endocarditis in IDUs is significantly associated with right-side localization (63.5% for any rightsided heart involvement vs 43.7% for any left-sided heart involvement; OR 2.24; 95% CI 1.55-3.23; p < 0.001). S. aureus is the microorganism most frequently isolated and is significantly associated with TV involvement. Any left-side involvement and age greater than 35 years are independently associated with mortality. HIV infection does not appear to have a significant effect on mortality.