Diagnosis of Sporotrichosis: Current Status and Perspectives

Definitive diagnosis of sporotrichosis is based on fungal detection in culture. Microscopic methods for the detection of Sporothrix yeast cells in clinical samples have low sensitivity. Although culture methods have high sensitivity, they also have some limitations, such as the time required to conclude the diagnosis, usually from 10 to 15 days, and the difficulty of obtaining an adequate clinical specimen for the test in cases of extracutaneous sporotrichosis. Serological methods are useful tools for a presumptive diagnosis of this infection. The most-used antigenic Sporothrix molecules are the peptide-rhamnomannan and secreted exoantigens. The enzyme-linked immunosorbant assay (ELISA) technique using the peptide-rhamnomannan has high efficiency, and it is useful in the serological follow-up of infection. Exoantigens were first used in immunoprecipitation and agglutination tests, but they have been used more recently in immunoenzymatic tests, with high sensitivity and specificity for both human and feline disease. A glycoprotein of 70 kDa was purified from Sporothrix exoantigens, presenting high immunogenicity, which allows its use in the development of more sensitive and specific methods for sporotrichosis serodiagnosis. Molecular methods of diagnosis can lower the time for diagnosis conclusion, but described methodologies in this field are scarce. In conclusion, the diagnosis of sporotrichosis is a challenging field, and the development of new serological and molecular diagnostic methods is mandatory.