Cryptococcosis (Torulosis)

Abstract

Epidemiological studies emphasize the wide distribution of Cryptococcus neoformans in nature. The disease process begins with inhalation of infected dust. There are wide variations in chest roentgenograms in pulmonary cryptococcosis making it necessary to include the disease in the differential diagnosis of pulmonary diseases of slow evolution. Cryptococcal involvement of the skin, mucous membranes, bones and joints usually represents hematogenous dissemination of the organism. The clinical symptomatology of cryptococcal meningitis and meningoencephalitis is dependent upon whether the cranial infection is diffuse or localized. Pathological changes in the nervous system are those of meningitis, meningoencephalitis or of demarcated granulomas.

The diagnosis of cryptococcosis is made by isolation of the organism and confirmed by an identification procedure that utilizes a number of biological and biochemical characteristics of the organism. C. neoformans is classified into three serotypes on the basis of type specific capsular polysaccharide, although cross reactions between these types and other microorganisms occur. Diagnostic serological procedures, including complement fixation tests, may provide early evidence of the disease. There is still no satisfactory antigen for eliciting skin hypersensitivity.

Biochemical studies of the organism reveal its requirement for thiamin and thiamin-moieties, the need for glutamic acid and glutamine, and its ability to assimilate readily carbohydrates and carbohydrate derivatives that are present in normal spinal fluid. Carbohydrate substrates serve as major sources of energy for biosynthesis. Infection of the central nervous system by C. neoformans is considered to be an example of exquisite parasitism that occurs when the exact nutritional needs of the parasite are supplied by host tissue.

Eleven patients with cryptococcal meningitis were treated with amphotericin B by intravenous and intrathecal routes. Seven of these improved considerably or returned to normal activity; four patients died. Of the four fatal cases, three patients had received only a minimal number of infusions of the antibiotic before death. The clinical responses were excellent in four patients with cryptococcal meningitis who received hyperimmune gamma globulin twice weekly, intravenous and intrathecal amphotericin B, and who were maintained on low thiamin diets.