Mycoses

Cryptococcus

Epidemiology
Common in immunocompromised patients ( AIDS )
An opportunistic fungal disease
There are about 50 species
Predominant pathogen is C.neofarmans
Other species such as C.albiodus and C.laurentii rarely cause disease in human
C. neoformans has 2 varieties ( neoformans and gattii )

Mycology

C.neoformans is found in temperate areas and found in pigeon droopings
C.gattii is found in tropics and not found in pigeon droopings
The two varieties are serotyped according to capsular polysaccharide
Four serotypes of C.neoformans ( A . B , C , D )
Serotype A is the most common
A&D serotypes are C.neoformans
B&C serotypes are C.gattii


Mycology
Growth of Cryptococcus takes 36 to 72 hours, and is slower than that of Candida and Saccharomyces species under the same conditions
White to creamcolored,smooth, mucoid colonies when grown on blood agar or Sabouraud dextrose agar
Transmitted by inhalation
C.neoformans grows at 37°C, whereas nonpathogenic species of Cryptococcus do not.
Produce melanin.

Life cycle

Pathogenicity

Polysaccharide capsule
Thermotolerance
Melanin production
Manitol production
Soluble cextracellular onstituents


PathogenicityRole of capsule
Antiphagocytic

Poor stimulation of T-cells and cytokines

Diseases
Pulmonary infection range (Asymptomatic to ARDS)
CNS infection (Meningitis)
Systemic infection
Skin infection

47-year-old man who underwent orthotopic heart transplantation one year ago has an x-ray showing a right upper lobe pulmonary nodule. The lung biopsy is shown. The most likely diagnosis is C.neoformans



47-year-old man who underwent orthotopic heart transplantation one year ago has an x-ray showing a right upper lobe pulmonary nodule. The lung biopsy is shown. The most likely diagnosis is C.neoformans

CNS infectionsCranial nerve manifestations

Decreased visual acuity
Blindness
Diplopia
Hear loss
Facial weakness


Skin lesions

Diagnosis

Capsule India Ink stain
Appear as a halo around the organism
Tissue biopsy stained by periodic
acid-Schiff
With the use of mucicarmine staining, the capsule look red

India ink stain of CSF

Gomori-methenaminesilver of biopsy

Culture

Sabouraud dextrose agar

White to creamcolored,smooth, mucoid colonies

Drugs
Amphotericin B (severe infection)
Fluconazole