Endocarditis Due to Actinomyces pyogenes

Actinomyces pyogenes, a rare cause of infections in humans, is part of the normal flora in many animals and is associated with suppurative or granulomatous lesions in various domestic animals. Microbiologically confirmed cases of A. pyogenes infections in humans have included soft tissue abscesses, otic infections, intraabdominal infections, cystitis, and bloodstream infections. Using criteria that allowed for definitive identification of A. pyogenes, we identified a fatal case of A. pyogenes endocarditis. To our knowledge, this represents the first confirmed case of A. pyogenes infection in the United States.