Cryptococcosis

• Cryptococcosis is most often seen in immune-compromised patients with impaired T cell immunity
• AIDS
• Corticosteroid therapy
• Solid organ transplantation (Renal transplant)
• Lymphoma and T cell dysfunction.
• Sarcoidosis
• Idiopathic CD4 + lymphocytopenia

Transmission 

• Cryptococcal infection occurs throughout the world sporadically. 
• Infection occurs from the environment usually by inhalation, especially of dust containing excreta of pigeons
• Infection is not transmitted from person to person.

Cryptococcal meningitis: 

• Hematogenous spread results in subacute or chronic meningitis or meningoencephalitis
• All untreated cases of cryptococcal meningitis are ultimately fatal. 
• About 5-8% of patients with AIDS develop cryptococcal meningitis.
• Signs and symptoms of cryptococcal meningitis
  • Headache
  • Fever
  • Change in mental status (ranging from confusion to lethargy to coma)
  • Blurry vision (and other cranial nerve deficits)
  • Neck stiffness
  • Sensitivity to light
  • Nausea and vomiting
  • Seizures
  • Papilledema

Lung infections: 

• Primarily cause lung infection
• Reactivation of old healed lesion may occur.
• Cryptococcal lung lesions do not calcify.

Skin and other infections: 

• Sometimes skin, lymph nodes, bones are involved.
• Superficial skin lesion.

Laboratory diagnosis

Specimens:  

• Specimens depends on clinical presentation and suspected disease conditions. 

Common specimens include :

• Spinal fluid (CSF)
• Tissue
• Exudates
• Sputum
• Blood
• Urine.

Microscopy and staining:

• Appear as a spherical, single or multiple budding, thick-walled yeast that is 2-15 μm (wide variation in size) in diameter.
• It is usually surrounded by a wide refractile capsule
• Maltese cross pattern under polarised light is seen 

India ink preparation

• Used as a rapid and inexpensive diagnostic tools
• Differentiates cryptococcus from other fungus. 
• Demonstration of heavily capsulated yeast cells  in CSF, exudates and urine establishes the diagnosis. 
• Sensitivity is low. 

Identification: 

• Identified by urease production and carbohydrate assimilation test
• Confirmed by direct immunofluorescence using a fluorescein-labeled anti-neoformans antibody.

Detection of Antigen: 

• Tests for capsular antigen can be performed on CSF and serum.
• Latex agglutination test is most useful in detection of cryptococcal polysaccharide antigen.
• Slide latex agglutination test has sensitivity of 90% in the cases of cryptococcal meningitis.

Detection of Antibody:

• Serum antibodies can be detected by agglutination and immunofluorescence.

Cryptococcal meningitis :

• Treated for two weeks with intravenous Amphotericin B
• Oral flucytosine