cryptococcosis

Introduction 

Cryptococcosis is a subacute or chronic infection caused by Cryptococcus neoformans, an encapsulated budding yeast

-Cryptococcal cells are typically present in bird droppings, particularly pigeon droppings 

C. neoformans is a yeast that is characterized by a thick polysaccharide capsule. 

-Polysaccharide capsule is the major virulence factor and basis for antigen testing

-it is most common cause of fungal meningitis

-Cryptococcosis is acquired by inhaling aerosols containing the yeast, which disseminate to other organs via blood 

Symptoms & Signs 

-The most common sites of infection are the lungs, central nervous system and skin 

Pulmonary cryptococcosis 

it is often asymptomatic or may cause an influenza-like illness with cough, fever, chest pain and dyspnea 

Meningoencephalitis

-Meningitis is the most commonly recognized and most serious form of cryptococcal disease

-In immunocompetent patients, it takes a slow, indolent course but in immunocompromised patients, it takes a more rapid course 

-Headache, fever, nausea, vomiting, neck stiffness, dizziness, somnolence, irritability, confusion, photophobia, seizures, cranial nerve defects, confusion, mental status changes

Cryptococcal skin disease: 

Cryptococcal cellulitis: resembles bacterial cellulitis, red, hot, tender plaques 

Cryptococcal dermatitis: resembles molluscum contagiosum, papular, nodular lesions with central umbilication 

Immune Reconstitution Syndrome

-A paradoxical clinical worsening which comes with enhanced inflammatory response due to immune reconstitution 

-worsening meningitis, increased intracranial pressure, hypercalcemia 

Diagnosis 

Histopathology and Cytology: globose or oval to lemon-shaped yeast with a polysaccharide capsule after staining with India ink, Gomori methenamine silver (GMS) and periodic acid–Schiff (PAS) stain, Mayer’s mucicarmine stain, and Masson–Fontana melanin stain; On diphenolic substrate, the phenol oxidase of cryptococcus produces melanin in the cell walls producing brownish colored colonies 

Antigen detection:  detection of Cryptococcal capsular antigen in serum, CSF, pleural fluid  

Culture: whitish mucoid colonies with spherical budding yeast cells surrounded by a thick non-staining capsule 

CSF: increased opening pressure, increased protein, decreased glucose, presence of cryptococcal capsular antigen

Imaging: Cryptococcal granulomatous calcifications on CXR; cryptococcomas in the brain on MRI, CT scan 

Treatment 

Pneumonia: Fluconazole, itraconazole, voriconazole, posaconazole

Meningitis: Amphotericin B, Fluconazole

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