[Tricuspid endocarditis caused by penicillin-resistant Staphylococcus aureus: 2 cases in parenteral drug addicts].

BACKGROUND: Staphylococcus aureus is the main causal agent of infectious endocarditis (IE) in intravenous drug addicts (IVDA) with most of the strains, isolated in Spain being resistant to penicillin and sensitive to methycillin, although the latter condition varied in recent years. Two cases of IE caused by S. aureus strains sensitive to penicillin in IVDA are presented. METHODS: All bacteremia episodes diagnosed in the Hospital General Penitenciario (Madrid) over a 33-month period (March 1991 to December 1993) were prospectively studied. Special attention was given to patients diagnosed of IE. Blood cultures were processed according to the usual technique by a non radiometric system. RESULTS: One hundred and four bacteremias were detected with 14 being produced by S. aureus. Ten episodes of the total number of bacteremias fulfilled criteria for IE with 2 being produced by strains of S. aureus sensitive to penicillin (CMI < 0.06 mu/ml). Both patients had coinfection by HIV. The clinical evolution prior to diagnosis was prolonged although clinical and microbiologic cure were achieved with intravenous beta-lactam antibiotics treatment, without complications. CONCLUSIONS: Despite the low incidence of the isolation of Staphylococcus aureus sensitive to penicillin (< 3%) recently observed in Spain, strains producing severe infections, showing patterns of sensitivity such as those found during the preantibiotic era, may still be isolated.