Background: Intravenous drug addicts (IVDA) are a group of patients in whom it is difficult to complete standard treatment of infectious endocarditis due to frequent antisocial behavior and in whom, once clinical improvement is achieved, voluntary discharge is frequently requested. This is why the evaluation of new treatment schedules tending to decrease the length of the same is of great interest. This non randomized study has the aim of knowing the efficacy of a short treatment with cloxacillin or vancomycin associated to gentamicin in right-sided endocarditis by methicillin-sensitive Staphylococcus aureus, comparing this with the standard schedule of 28 days.
Methods: This series was made up of IVDA patients diagnosed of right endocarditis by S. aureus. Inclusion criteria were the presence of intravenous drug addiction, isolation of methicillin-sensitive S. aureus in 2 or more blood cultures and achievement of the diagnostic criteria of right-sided endocarditis. Two schedules were used: a) standard: cloxacillin or vancomycin for 4 weeks, associating aminoglucoside in the first 3-5 days; b) short; cloxacillin or vancomycin associated to gentamicin for 2 weeks with no ulterior treatment. The study was not randomized and the treatment of 2 weeks was compared with historic controls treated for 4 weeks. The criteria evaluated were those of clinical cure, relapse, appearance of complications during treatment and mortality.
Results: Both the standard treatment and the combination of cloxacillin or vancomycin with gentamicin for 2 weeks cured 100% of the episodes of right endocarditis by S. aureus. There were no relapses and mortality was nul. Neither were there any differences between the two groups with regard to appearance of complications.
Conclusions: In intravenous drug addict patients with right-sided endocarditis by methicillin S. aureus, the association of cloxacillin and gentamicin for 2 weeks is an effective alternative to long (4 week) treatments with only one antibiotic. The low number of cases treated with vancomycin does not allow conclusions to be drawn on its efficacy.