C-191. Tricuspid Valve and Pacemaker Endocarditis due to Pseudallescheria boydii (Scedosporium apiospermum)

J. A. Laurini, J. E. Carter, A. G. Kahn;
Univ. of South Alabama, Mobile, AL.

Invasive mycotic infections are an important cause of death in immunocompromised hosts. Although opportunistic fungal infections are more commonly due to Aspergillus spp. and Candida spp., an increasing number of fungi, formerly regarded as minor pathogens, are being reported as a cause of serious infections in this setting. We report the case of a 78 year-old male with a past medical history significant for diabetes mellitus and cardiac arrhythmia with permanent pacemaker placement who was transferred to our institution after a transesophageal echocardiogram revealed vegetative masses on the tricuspid valve and on the pacemaker lead. The patient underwent cardiac surgery with resection of the tricuspid valve and removal of the pacemaker. The patient died shortly after the surgical procedure. At autopsy, white-yellow, soft, friable vegetations were on the residual anterior and posterior leaflets of the tricuspid valve. The lungs appeared congested with multiple irregularly-shaped, brown, subpleural lesions measuring up to 1.6 cm. The pulmonary vasculature contained white-pink, firm emboli. On microscopic examination, the tricuspid valve vegetations and the lung lesions contained thick, hyaline, septate hyphae admixed with fibrin strands and inflammatory cells. Most of the pulmonary emboli contained aggregates of hyaline hyphae. Culture on standard mycologic media demonstrated Scedosporium apiospermum, the asexual form of Pseudallescheria boydii. Only ten cases of endocarditis due to this fungus have been reported so far in the English literature, including one case associated with a permanent pacemaker. The morphological similarities of P.boydii in tissue sections to other more common filamentous fungi such as Aspergillus spp. require adequate correlation with fungal cultures for proper classification. This becomes particularly important since P.boydii is usually resistant to amphotericin B, the agent traditionally used for the treatment of disseminated aspergillosis.