​Infectious Diseases and Microbiology -Cryptococcosis (Cryptococcus neoformans)

​Infectious Diseases and Microbiology -Cryptococcosis (Cryptococcus neoformans)
Cryptococcosis
The etiology of cryptococcosis is Cryptococcus neoformans, which is spread by inhaling yeast cells from soil and roosting areas tainted with pigeon droppings. The disease cannot be spread from person to person. C. neoformans exclusively exists as the yeast form; it is not dimorphic. The most frequent cause of meningitis in AIDS patients is cephalosporans. Immunocompromised individuals, including those with HIV and AIDS, as well as those who have had organ transplants, are at risk for infection.

In patients with AIDS, cryptococcosis causes slow-moving CNS symptoms that eventually lead to chronic meningitis. Pneumonia caused by C neoformans might be mild or asymptomatic and typically goes away on its own. In disseminated illness, skin lesions and bone involvement are common.
 
The organism enters the lungs through breathing, and then it spreads hematogenously to the meninges and brain. The polysaccharide capsule of Candida neoformans promotes spread by preventing lung neutrophils and macrophages from phagocytosing the organism. Immunity mediated by T cells is the main factor influencing resistance.

The diagnosis of cryptococcosis can be made with excellent sensitivity and specificity using latex agglutination to detect the cryptococcal polysaccharide antigen in serum or cerebrospinal fluid (CSF). About 50% of the time, CSF stained with India ink shows encapsulated yeast as cells encircled by a transparent halo.
 The combination of flucytosine and amphotericin B is used to treat disseminated cryptococcosis. In AIDS patients, fluconazole is used to stop illness relapse. Immunocompromised patients should take precautions by avoiding regions where pigeon excreta is present.