Endocarditis caused by oxacillin-susceptible Staphylococcus aureus with reduced susceptibility to vancomycin? First report in Argentina: a case report.

BEATRIZ PERAZZI; NATALIA BELLO; MARTA MOLLERACH; CARLOS VAY; MARÍA BEATRIZ LASALA; ANGELA FAMIGLIETTI

Journal of Medical Case Reports

BIOMED CENTRAL LTD

Lugar: Londres, Inglaterra; Año: 2011 vol. 5 p. 292 - 297

1752-1947

Introduction: Staphylococcus aureus is the most common cause of acute infective endocarditis.Recent reports have described heteroresistance to vancomycin associated with methicillin-resistant Staphylococcusaureus. We present the first case report in Argentina of the failure of treatment with vancomycin in endocarditiscaused by methicillin-susceptible Staphylococcus aureus containing subpopulations with reduced susceptibility tovancomycin.Case presentation: We report the case of a 66-year-old Hispanic man with infective endocarditis complicated byseptic emboli in the lumbosacral spine and the left iliopsoas muscle. This disease was caused by methicillinsusceptibleStaphylococcus aureus containing subpopulations with reduced susceptibility to vancomycin. He wasinitially treated with cephalothin and gentamicin but developed a rash caused by beta-lactams and interstitialnephritis. For that reason, the treatment was subsequently switched to vancomycin but he failed to respond. Theinfection resolved after administration of vancomycin in combination with gentamicin and rifampin.Conclusion: Our case report provides important evidence for the existence of subpopulations of methicillinsusceptibleStaphylococcus aureus that have reduced susceptibility to vancomycin which would account fortreatment failure. Our case raises an alert about the existence of these strains and highlights the need todetermine the vancomycin minimum inhibitory concentration of Staphylococcus aureus to screen for the presenceof strains that have reduced vancomycin susceptibility at different infection sites.