Rare and emerging fungal pulmonary infections.

The frequency and diversity of serious fungal infections are increasing. Persons who are severely immunocompromised are particularly vulnerable to infection from unusual molds and yeasts that are often found naturally in the environment. Clinical manifestations from these unusual fungal infections range from colonization of airways to chronic localized lesions to acute invasive or disseminated disease. When present, rare and emerging fungi are often isolated from the respiratory tract during a severely immunosuppressed state, and diagnosis requires isolation and identification of the infecting organism. Histopathology is often required to differentiate tissue invasion from airway colonization. There are no diagnostic serologies, and radiological exams are not specific. Furthermore, many emerging opportunistic molds demonstrate in vitro resistance to the older azoles and amphotericin B. As a result, successful treatment may require adjunct surgical debridement and, when possible, reconstitution of the host immune system. Also, the newer triazoles such as voriconazole and posaconazole may be useful to treat some of these infections caused by rare and emerging molds.