Respiratory Infections

Abstract

Candida spp account for the large majority of fungal infections. The incidence of nosocomial fungal infections has been steadily increasing over the last several years because of the increasing number of patients treated in intensive care units, the common administration of antimicrobial agents, and the use of invasive measures in these patients. The route of infection in Candida pneumonia is endobronchial in cases of aspiration or hematogenous in patients with candidemia. Because colonization of the lower respiratory tract with Candida is common, especially in the intubated and mechanically ventilated patient, the diagnosis cannot be established microbiologically. Even quantitative cultures of respiratory secretions cannot distinguish colonization from infection. Although serologic markers of Candida infection or candidemia are commercially available, the diagnosis of Candida pneumonia is best made by histologic examination of lung tissue. According to the route of infection, characteristic histologic signs (e.g., budding yeast, pseudohyphae) can be documented. However, because of the uncharacteristic clinical presentation of Candida pneumonia, early presumptive therapy may be initiated in some cases. Amphotericin B remains the drug of choice in patients without bacteriologic identification of the fungus, because of resistance of some non-albicans Candida species against fluconazole. However, patients with Candida albicans pneumonia may profit from the lower toxicity of fluconazole therapy. Because mortality even of treated Candida pneumonia remains high, preventive measures are of particular interest. Risk factors for candidemia have been identified (e.g., neutropenia, mechanical ventilation) and may serve to guide prevention of Candida pneumonia.