Actinobacillus actinomycetemcomitans causing a mediastinal abscess.

We report what may be the first documented case of an anterior mediastinal abscess due to infection by Actinobacillus actinomycetemcomitans. This small, fastidious Gram-negative coccobacillus is a normal component of the oral flora of healthy individuals,' but rarely a human pathogen. It was first described in 1912 by Klinger2 in association with actinomycosis and has since been identified as the sole aetiological agent in at least 52 cases of bacterial endocarditis in North America and Europe and in isolated cases of brain abscess, meningitis, urinary tract infection, pneumonia, thyroid abscess, and soft tissue and wound infections.36