Cryptococcosis

C. neoformans causes cryptococcus, especially cryptococcal meningitis. C. neoformans is an oval, budding  yeast  surrounded  by  a  large polysaccharide capsule. It occurs widely in nature and grows abundantly in soil containing bird droppings. The organism is most often inhaled and spread  hematogenously  from  the  lungs.  Lung infections range from asymptomatic to pneumonia. Cryptococcosis is the most common encapsulated infection  in  the  immunocompromised host.  The organism disseminates hematogenously to the central nervous system (meningitis) andother organs.  It  can  be  cultured  from  cerebral  spinal fluid  (CSF)  or  diagnosed by  serologic tests  for either antibody or  antigen. Amphotericin B  and flucytosine are used to treat cryptococcal meningitis.

Ans. is ‘a’ i.e., Cryptococcus

Capsular antigen is detected in CSF or serum by latex agglutination.

Ans. is ‘c’ i e., Urease negative

Cryptococcus neoformans is distinguished from other non-pathogenic crvptococci by ‑

– Ability to grow at 37°C

Lack of fermentative ability

–   Ability to hydrolyze urease (urease positive)

–   Formation of brown pigment on niger seed agar

–   Ability to assimilate inositol

Ability to produce phenole oxidase.

Ans. is ‘d’ i.e., Kidney

Crvptococcosis

• Acquired by inhalation of the fungus into the lungs.
• Rarely acquired through skin or mucosa.
• Pulmonary infection has a tendency toward spontaneous resolution and is frequently asymptomatic.
• Silent hematogenous spread to the brain occurs, especially in basal ganglia or the head of the caudate nucleus.
• C/Fs –  Self limiting pulmonary infection Most common form of cryptococcosis (Green wood) Meningoencephalitis (most patients have at the time of diagnosis)

Pulmonary symptoms

Skin lesions (10%)

Osteolytic lesions in bone (4%)

Remember

• Cryptococcus in AIDS patient has less signs and symptoms.
• Focal lesion called cryptococcomas are more common in previously normal patient.
• Self limiting pulmonary infection is the most common form of cryptococcosis, but most patient present with meningoencephalitis.
• Headache is the most common symptom.
• Cryptococcal lung lesions do not calcify.

Ans. is ‘a’ i.e., Renal transplant recipient

Predisposing factors for crvptococcus

• AIDS (most common) -4 when CD, T cells <200/ L                       • Sarcoidosis
• Glucocorticoids therapy                                                                 • Lymphoma
• Solid organ transplantation (Renal transplant)                                • Idiopathic CD₄ + lymphocytopenia

Ans. is ‘a’ i.e., Cryptococcus neoformans

• Maltese cross pattern under palarized light is seen in :- Babesia, Cryptococcus, Aspergillus nidulans, starch granules and lipid (cholesterol) droplets.

“Fungal ball due to Aspergillus nidulans have a propensity to produce pale staining thick walled non-viable null cells that show maltese cross bifringence when examined under polarized light”.

“On polarized light the spores in cryptococcus give maltese cross appearance”.              – Atals of deep mycosis

“Babesia microti is associated with maltese cross forms and ring forms”.                – Barbara J. Bain

“Starch granules and fat (cholesterol) droplets produce maltese cross pattern in polarized light”.

Ans. B: Cryptococcus neoformans

Such organisms include the bacteria that cause tuberculosis or syphilis and fungi such as Cryptococcus neoformans or Coccidioides immitis.

These fungi are more likely to cause chronic meningitis in people with a weakened immune system, such as those with human immunodeficiency virus (HIV) infection or acquired immunodeficiency syndrome (AIDS).

Ans. B: Amphotericin B

Cryptococcosis that does not affect the central nervous system can be treated with fluconazole alone.

Cryptococcal meningitis should be treated for two weeks with intravenous Amphotericin B and oral flucytosine. Main disadvantage of Amphotericin B includes nephrotoxicity.

Ans. B: Cryptococcus

In immunocompetent patients, cryptococcal infection is usually asymptomatic, self-limited, and confined to the lungs.

In persons with advanced HIV infection (e.g., those with CD4 counts <100 cells/ µL), Cryptococcus may cause life-threatening illness, either from a new exposure or through reactivation of a previously acquired latent infection.

In HIV-infected patients, Cryptococcus can infect almost all organs in the body, but most commonly causes meningitis or meningoencephalitis.

Ans. is `b i.e., Urease negative

CRYPTOCOCCUS NEOFORMANS

• The only pathogenic yeast
• Four capsular serotypes – A, B, C and D
• It has polysaccharide capsule
• Most infections in immunocompromized patients are caused by serotype A.
• Pigeon droppings commonly contains serotype A and D.
• Eucalyptus tree contain serotype B.
• It is urease positive.

Mode of transmission

• By inhalation of the fungus into the lung (most common)
• Through skin or mucosa (some times).

Ans. is ‘c’ i.e., India ink

Unstained wet preperations of CSF mixed with drop of India ink or nigrosine demonstrate the capsule as a clear halo.

Methenamine silver or periodic acid-Schiff are used for staining a tissue sample.