DIAGNOSIS OF SYSTEMIC FUNGAL-INFECTIONS

Most of the systemic fungal infections seen in Norway are caused by Candida species. The clinical picture is very similar to that which is seen in systemic bacterial infections. However, some patients may develop a more characteristic picture such as skin lesions or eye involvement (endophthalmitis). Blood culture is important for diagnosis, but the sensitivity is rather low (approx. 50%). A new blood culture technique (lysis centrifugation), however, has improved this. Histology and culture of biopsy material, particularly from skin lesions, help establish a proper diagnosis. A number of serological tests are available. Antibody tests have a limited value. False negative results are frequently observed in immunocompromised patients and the diagnostic value is also reduced because positive results are found in patients colonized with yeasts. Methods for detection of free Candida antigen have low sensitivity. The reported specificity for one of the commercial tests (Cand-Tec) has varied from 34% to 100%. The diagnosis of cryptoccal meningitis is usually easy as long as the possibility of this disease is kept in mind. Cryptococcus neoformans is usually detected by direct microscopy and culture of the cerebrospinal fluid. A latex test for the detection of antigen in the spinal fluid has high sensitivity and specificity.