Infective endocarditis due to Abiotrophia defectiva: a report of two cases.

Background and Aim of the Study: Endocarditis due to Abiotrophia sp. is rare and often associated with negative blood cultures. The rates of treatment failure, infection relapse and mortality are higher than in endocarditis caused by other viridans streptococci.
Methods: A retrospective review of A. defectiva endocarditis in a patient with prosthetic aortic valve and in a patient with Marfan syndrome was performed.
Results: A. defectiva, susceptible to penicillin (MIC 0.064 mg/l and 0.016 mg/l, respectively) was isolated from blood cultures of both patients. Treatment with penicillin and gentamicin was started in both patients. Since the first patient developed a macular rash and leukopenia, penicillin was substituted with ceftriaxone. Both patients responded well to antibiotic treatment, did not need prosthetic valve insertion or reinsertion, and were without any sequelae at one year follow up.
Conclusion: Standard treatment of bacterial endocarditis with penicillin and gentamicin was effective in both patients. In contrast to previous reports, the present patients had a favorable outcome on completion of treatment and at one-year follow up.