Endocarditis Caused by Penicillin- Resistant Viridans Streptococci: 2 Cases and Controversies in Therapy

Although penicillin-resistant viridans streptococci have been isolated from samples from the mouth, blood, and wounds in increasing numbers, viridans streptococci isolated from patients with endocarditis have remained sensitive to peni-cillin for the past 5 decades. We report the cases of 2 patients with penicillin-resistant viridans streptococcal endocarditis, review 6 other cases from the literature, and summarize 2 studies that used an animal model of penicillin-resistant viri-dans streptococcal endocarditis. In 1999, we were consulted regarding 2 patients with penicillin-resistant viridans streptococcal endocarditis. The cases of these patients and 2 other cases reported in 1999 [1, 2] raise the question of whether this disease is becoming increasingly com-mon, as has endocarditis caused by other drug-resistant, gram-positive organisms such as Staphylococcus aureus or enterococci