Cryptococcus neoformans infections

CSF may be unrevealing. Opening pressures often high. Higher numbers of fungal organisms in the CSF is associated with higher opening pressures. Must check cryptococcal antigen

About

• Affects immunocompromised.
• An encapsulated yeast 2 to 15 um in greatest diameter
• Very thick-walled sugar-based capsule which can prevent immune attacks
• Needs aggressive antifungal therapy
• Can cause pneumonia and meningitis

Aetiology

• Infection from bird droppings and the soil enters via the pulmonary route
• Pulmonary infection can via blood spread to the brain
• Seen in AIDS and those with abnormal Cell mediated Immunity (see below)

Defective cell mediated immunity

• AIDS, Immunosuppression for organ transplantation
• Reticuloendothelial malignancy, Corticosteroid treatment, Sarcoidosis

Clinical

• Nausea, Headache, fever, malaise, Can be subtle
• Basal meningitis causes cranial nerve palsies
• Stroke like syndrome, Space occupying lesion
• Chest disease - fever, malaise, cough with scant sputum, ARDS
• Cryptococcal skin lesions look like molluscum contagiosum
• Myocarditis, Hepatitis, Chorioretinitis, Renal abscess

Investigations

• FBC, U&E, CRP, HIV test , CXR - may be abnormal
• CT Head: first in immunocompromised with high risk of mass lesions
• CSF: elevated pressure and protein and lymphocytes. Cryptococcal meningitis often increases ICP. This results from a polysaccharide capsule (contributing to the fungus' large size) that blocks the transport of CSF through the arachnoid granulations, raising ICP. High ICP is more common in HIV+ due to higher fungal burdens
• CSF India ink stain usually shows encapsulated budding cells in up to 90% of cases
• Cryptococcal antigen test needed to make the diagnosis
• Blood/urine/sputum and even bone marrow can be cultured

Cryptococcal abscesses

Management

• IV liposomal Amphotericin B is given for 2 weeks. Beware nephrotoxicity.
• Ongoing Fluconazole OD for AIDS patients.
• Consider commencing HAART at 2 weeks later to minimise risk of IRIS