An experimental study was conducted between January 2002 and April 2003 for the detection of
delayed hypersensitivity to Fonsecaea pedrosoi metabolic
antigen (
chromomycin) in skin tests. A total of 194 subjects were attended by spontaneous demand at the Infectious and
Parasitic Diseases outpatient clinic of the Federal University of Maranhão-UFMA and at the Department of Microbiology, Federal University of Minas Gerais-UFMG and classified into three groups: patients with
chromoblastomycosis caused by F. pedrosoi (n=20), healthy subjects (n=86) and patients with other diseases (n=88). For the skin test, 0.1 ml of the
antigen was applied to the anterior side of the right forearm and 0.1 ml Smith medium was applied to the anterior side of the left forearm as control. The results were analyzed 48 h after inoculation of the
antigen and an induration >/= 5 mm was considered to indicate a positive test. A cellular immune response to
chromomycin was detected in 18 (90.0%) of the 20 patients with
chromoblastomycosis caused by F. pedrosoi, and one of the patients with a negative test had reactional
leprosy. Eighty-five (98.8%) of the 86 healthy subjects presented a negative reaction and only one reacted positively to the
antigen. The skin test was negative in all 88 (100%) patients with other diseases, such as
dermatophytosis,
paracoccidioidomycosis, pulmonary aspergilloma,
candidiasis,
pityriasis versicolor,
tuberculosis,
leprosy, tegumentary
leishmaniasis and
syphilis, and one case of
chromoblastomycosis caused by Rhinocladiella aquaspersa.
Chromomycin was effective in detecting
delayed hypersensitivity in patients with
chromoblastomycosis caused by F. pedrosoi, with a sensitivity and specificity of 90.0% and 98.8%, respectively. These results suggest that this
antigen can be used in the auxiliary diagnosis of the disease and also in epidemiological studies for determination of the prevalence of
chromoblastomycosis infection in endemic areas.