Underdiagnosed and Potentially Lethal

CHEST I 103 I 6 I JUNE, 1993 1887 Pulmonary actinomycosis usually occurs as a result of the aspiration of oropharyngeal material in the setting of poor dental hygiene or oral trauma. When pathogenic, it is invasive, often mimicking a malignancy in presentation and macroscopic appearance. Endobronchial disease due to this pathogen rarely is reported. Ariel et al recently described five patients presenting with endobronchial actinomycosis presenting in a subacute fashion, similar to the presentation in our patient. Endobronchial infection is thought to be due to implantation of infected aspirated material, lymphohematogenous spread to the peribronchial region, or endobronchial implantation of infected secretions from draining cavitary lesions. Although the diagnosis of actinomycosis was presumptive since the cultures of all specimens were negative, this was not an unexpected finding in light of antibiotic therapy administered prior to bronchoscopy. In addition, the finding of a sputum culture positive for H influenzae is common in the setting of Actinomyces pulmonary infection. Coexisting organisms such as fusobacteria, streptococci and Eikenella may be cultured as well. Even among immunocompromised hosts, such as patients on chronic steroid therapy or cancer chemotherapy, actinomycosis has not been shown to have an increased prevalence of infection. Actinomyces is a rare pathogen in the HIVinfected population.” This is most likely due to the partial susceptibility of the organism to antibiotics commonly used to treat persons with AIDS such as trimethoprim-sulfamethoxazole, isoniazid, rifampin and the cephalosporins. Why this particular patient developed actinomycosis infection with endobronchial disease is unclear. Although his oral hygiene appeared to be maintained, there may have been unsuspected aspiration of oropharyngeal secretions which subsequently led to endobronchial disease. The possibility that the endobronchial tissues may have been secondarily involved from a more distal infection, as seen in tuberculosis, also must be entertained. The subacute presentation, the initial lack ofresponse to orally administered antibiotics and the development of a new infiltrate while receiving a broadspectrum intravenously administered antibiotic regimen is consistent with this infection. Actinomycosis also must be considered when obstructing lesions are noted at the time of bronchoscopy in a patient with AIDS and a suspected pulmonary infection.