[Non-toxic Corynebacterium diphtheriae septicemia with endocarditis in an earlier healthy adult. First case and review of the literature].

Corynebacterium diphtheriae septicaemia is rarely encountered, usually in very particular situations: children with severe congenital heart disease or after heart surgery. Rare cases have been reported in immunodepressed adults or drug addicts. We observed a case in a formerly healthy 41-year-old woman who was hospitalized for fever unresponsive to bacampicillin. In this patient, no portal of entry could be identified; there was no history of past surgery nor drug abuse. The patient was not immunodepressed and HIV serology was negative. The last anti-diphtheria vaccination had been given at the age of 12 years. Corynebacterium diphtheriae var. metis was identified on five blood cultures. The in vitro Elek test revealed that the strain was non-toxic. Echocardiography did not show any signs until the fourth examination performed 1 month after onset of fever and 15 days after initiating effective adapted antibiotic treatment with amoxicillin-clavanic acid. Mitral vegetations with grade 2 regurgitation completely regressed after 5 weeks of treatment. After 5 months of follow-up, the patient is in good health and no mitral damage has been observed. This is to our knowledge the first case report of Corynebacterium diphtheriae in a formerly healthy adult. In the literature 12 other cases in adults all concerned immunodepressed subjects or drug abusers. The question is raised as to whether Corynebacterium diphtheriae is undergoing mutation. The germ could persist as a commensal host and explain a certain number of the recent observations in drug abusers and immunodepressed patients.