++
For further information, see CMDT Part 36-06: Cryptococcosis
+++
Essentials of Diagnosis
++
Predisposing factors
Most common cause of fungal meningitis
Symptoms of headache, abnormal mental status; meningismus seen occasionally, though rarely in patients with AIDS
Demonstration of capsular polysaccharide antigen in cerebrospinal fluid (CSF) diagnostic
+++
General Considerations
++
Infection is due to
Cryptococcus neoformans, an encapsulated budding yeast that is found worldwide in soil and in dried bird droppings
Cryptococcus gattii is a closely related species that also causes disease in humans, although it may affect more ostensibly immunocompetent persons
C neoformans accounts for majority of disease worldwide and is especially problematic in immunocompromised patients
C neoformans variety gattii causes localized infections (cryptococcomas) in tropical climates and has close association with eucalyptus plants
C neoformans has a special predilection for the CNS and is the most common fungal cause of meningitis
The polysaccharide capsule is a major virulence factor and provides the basis for antigen testing that is widely available and quite useful in establishing the diagnosis
Infection is acquired through inhalation of the organisms into the lungs where infection may remain localized, heal, or disseminate
Progressive pulmonary disease can occur in either HIV-infected or noninfected patients in the absence of dissemination
Disseminated disease in immunocompetent patients can be especially recalcitrant to therapy
++
++
Disseminated cryptococcosis
Most commonly manifests as meningitis, which usually begins with headache, then confusion
Cranial nerve abnormalities, nausea, and vomiting may occur
Nuchal rigidity and meningeal signs in about 50%, but uncommon in patients with AIDS
C gattii infection frequently presents with respiratory symptoms along with neurologic signs caused by space-occupying lesions in the CNS
Primary C neoformans infection of the skin may mimic bacterial cellulitis, especially in persons receiving immunosuppressive therapy such as corticosteroids
The immune reconstitution inflammatory syndrome (IRIS), which is paradoxical clinical worsening associated with improved immunologic status, has been reported in HIV-positive and transplant patients with cryptococcosis as well as non-AIDS patients being treated for C gattii infection
+++
Differential Diagnosis
++
++
In HIV-infected patients with cryptococcosis, serum cryptococcal antigen positive in 95%
In patients with cryptococcal meningitis, CSF shows
Up to 50% ...