Aggregatibacter actinomycetemcomitans Causing Empyema Necessitans and Pyomyositis in an Immunocompetent Patient

Abstract

Empyema necessitans is a relatively rare clinical entity in which the empyema extends through the parietal pleura into the adjacent soft tissue and musculature of the chest wall. It usually occurs due to inadequate treatment of a primary lung infection. Aggregatibacter (formerly Actinobacillus) actinomycetemcomitans is a facultative anaerobic gram-negative coccobacillus that is part of the normal oral flora. Infections due to this organism usually result from aspiration in conjunction with dental disease or trauma to the oral mucosa resulting in pneumonia or empyema. It often coinfects with Actinomyces and is known to cause empyema necessitans. Cases of monomicrobial empyema necessitans due to Aggregatibacter actinomycetemcomitans in adults have rarely been reported with four such publications found on review of the literature. We present a patient with severe periodontitis who developed empyema necessitans due to Aggregatibacter actinomycetemcomitans likely from aspiration complicated by pyomyositis of the right triceps brachii and a left posterior thigh abscess.

Keywords: aggregatibacter actinomycetemcomitans; empyema necessitans; empyema necessitatis; immunocompetent; pyomyositis.

Figure 1. Musculocutaneous fistula on posterior surface of right upper arm with scant purulent drainage.

Figure 2. CT with contrast of the chest showing an abscess in the right lung (solid arrow) with extension through the pleura and into the soft tissue and musculature of the right chest wall (dashed arrow).

Figure 3. Vacuum-assisted closure of wound of right upper chest wall following the initial surgical debridement.