DOI: 10.1097/01.inf.0000057438.07919.a1
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Issn Print: 0891-3668
Publication Date: 2003/03/01
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Excerpt
Cryptococcus is an encapsulated pathogenic yeast found worldwide in soil contaminated with bird droppings. Disease in humans is caused by two varieties of Cryptococcus neoformans, var. neoformans and var. gattii.
Pulmonary infection results after inhalation of airborne spores. Primary pulmonary disease is often asymptomatic but can present with cough, fever and chest pain. In the immunocompetent individual pulmonary disease often resolves spontaneously. Hematogenous dissemination to extrapulmonary sites, especially the central nervous system (CNS), skin and bones can occur, most frequently in the setting of underlying immunodeficiencies. 1–4 Patients with defects in T cell immunity are at increased risk, with 80 to 90% of severe cryptococcal disease occurring in patients infected with HIV. Patients who have undergone organ transplantation are also at increased risk because of high dose steroid therapy. 2, 3, 5
In the pediatric patient cryptococcal infection is rare. Even in those children infected with HIV, infection is much less common than in adults with HIV. 6 Gonzalez et al. 6 reported an annual incidence of cryptococcosis in HIV-infected children of 0.1% in their review of 473 patients. Frequency of disease in immunocompetent children is unknown but is assumed to be even less than in patients with immunodeficiency. It is unknown why occurrence of disease is lower in children than in adults, but it has been postulated that lack of exposure to the organism may be a contributing factor. 7 Our case is unusual in that pulmonary disease progressed to include a second site in a pediatric patient with no detectable immunodeficiency. Possibly the patient developed disease because of repeated intense exposure to dirt contaminated with excessive bird droppings while training as a cross-country runner on dirt roads.
Definitive diagnosis of cryptococcal infection requires culture of the organism. Yield from culture is dependent on the quality and the processing of specimens. Laboratory personnel should be notified when C ryptococcus is suspected for proper handling and processing of the specimen. Detection of Cryptococcus antigen by latex agglutination test in CSF, serum or urine is highly sensitive and specific. This test is positive in 90% or more of patients with cryptococcal meningitis. 2, 3 As was the case in our patient, diagnosis is often made by detection of cryptococcal antigen in combination with histopathologic findings. High titers of cryptococcal antigen in serum and CSF before treatment have been correlated with high mortality and poor outcome. 2 Antigen titer is also useful in monitoring therapeutic response to treatment in patients with cryptococcal infection. 2, 6
Practice guidelines for the treatment of cryptococcal disease have recently been published. 8 Treatment is dependent on the anatomic site of disease and the immune status of the patient. In immunocompetent patients with self-limited pulmonary disease, often no treatment is required. Progressive symptomatic infection warrants treatment with fluconazole for 3 to 6 months. All individuals with significant cryptococcal infection require evaluation of cerebrospinal fluid because of the predilection for infection of the CNS. For those patients with CNS disease, treatment with amphotericin in combination with flucytosine is indicated. All patients infected with HIV who develop cryptococcal disease require treatment.
