Cryptococcosis

Cryptococcosis


Risk Factors

  • 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.
Treatment

Cryptococcal meningitis :

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

Exam Important

Risk Factors

  • Cryptococcosis is most often seen in immune-compromised patients with impaired T cell immunity
  • AIDS
  • Solid organ transplantation (Renal transplant)

Cryptococcal meningitis: 

  • Hematogenous spread results in subacute or chronic meningitis or meningoencephalitis

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

  • Maltese cross pattern under polarised light is seen 

India ink preparation

  • Differentiates cryptococcus from other fungus. 
  • Demonstration of heavily capsulated yeast cells  in CSF, exudates and urine establishes the diagnosis. 

Identification: 

  • Identified by urease production and carbohydrate assimilation test

Detection of Antigen: 

  • Latex agglutination test is most useful in detection of cryptococcal polysaccharide antigen.

Treatment

Cryptococcal meningitis :

  • Treated for two weeks with intravenous Amphotericin B
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