Cardiobacterium hominis endocarditis in a patient with a hypersensitivity reaction to penicillin. Successful treatment with partial resection of the posterior mitral valve leaflet and antibiotic therapy with cefazolin.

A 43-year-old patient with preexisting mitral valve prolapse and Cardiobacterium hominis endocarditis with partial destruction of the posterior mitral valve leaflet is described. Successful treatment was achieved with partial resection of the posterior mitral valve leaflet and antibiotic therapy. Because of a hypersensitivity reaction, initial therapy with penicillin G and gentamicin was stopped and substituted with cefazolin. No relapse of endocarditis was observed after 12 months of follow-up. Using micro broth dilution technique the isolated strain was shown to be most susceptible to penicillin G, cephalothin, and ciprofloxacin, with minimal inhibitory concentrations of 0.00025, 0.004, and 0.002 mg/l, respectively; and with minimal bactericidal concentrations (99.9% killing) of 0.25, 0.12, and 0.008 mg/l, respectively. We conclude that cephalosporins of the first generation or ciprofloxacin may be good alternatives to penicillin G in the treatment of C. hominis infection in patients known to be hypersensitive to penicillin.