Chapter 8: Fungal infections in immunocompromised patients.

Pulmonary complications are the most common cause of morbidity and mortality in immunocompromised patients, who lack of the basic mechanisms of cellular defense. Regardless of the cause of the immunodeficiency, the most common complications are infections (bacterial, viral or fungal). Among the fungal infections, aspergillosis is the most common (incidence, 1-9%; mortality, 55-92%) following organ transplant. Although pulmonary involvement is the most common form of aspergillosis, central nervous system involvement and sinusitis are not uncommon. On CT scans, the halo sign represents an area of low attenuation around the nodule, revealing edema or hemorrhage. The gold standard for the diagnosis is the culture identification of the fungus in sputum, BAL fluid or biopsy samples. Failing this identification, the detection of galactomannan, which is one of the fungal wall components, has shown sensitivity and specificity of 89% and 98%, respectively. Amphotericin B, liposomal amphotericin B, caspofungin and, especially, voriconazole are effective against the fungus. Although Pneumocystis jirovecii pneumonia can be fatal, the incidence of this disease has decreased due to the prophylactic use of trimethoprim-sulfamethoxazole. In immunocompromised patients presenting with dyspnea and hypoxemia, screening for fungi is indicated. A 14- to 21-day course of trimethoprim-sulfamethoxazole in combination with corticosteroids is usually efficacious. Another rare fungal infection is disseminated candidiasis, which is caused by Candida spp.