Molecular identification of unusual Mycetoma agents isolated from patients in Venezuela

Abstract

Mycetoma is a chronic granulomatous, subcutaneous disease endemic in tropical and subtropical countries. It is currently a health problem in rural areas of Africa, Asia and South America. Nine cases of mycetoma were analysed in a retrospective study. All isolates were identified by morphological features. The level of species identification was reached by molecular tools. Definitive identification of fungi was performed using sequence analysis of the ITS of the ribosomal DNA region and the ribosomal large-subunit D1/D2. Identification of actinomycetes was accomplished by the 16S rRNA gene sequence. Six unusual clinical isolates were identified: Aspergillus ustus, Cyphellophora oxyspora, Exophiala oligosperma, Madurella pseudomycetomatis, Nocardia farcinica and Nocardia wallacei. The prevalence of mycetoma in Venezuela remains unknown. This study represents the first report in the literature of mycetoma caused by unusual pathogens identified by molecular techniques.

Diagnostic implications of mycetoma derived from Madurella pseudomycetomatis isolates from Mexico

“…The M. pseudomycetomatis case from Venezuela was treated for 72 months with itraconazole and was also cured. 24 This is similar to the response rate for M. mycetomatis in which 56.2% 30 to 69% 31 cases responded to azole treatment.…”

“…Indeed, the cases from father and son were both treated with itraconazole and both showed clinical improvement. The M. pseudomycetomatis case from Venezuela was treated for 72 months with itraconazole and was also cured 24 . This is similar to the response rate for M. mycetomatis in which 56.2% 30 to 69% 31 cases responded to azole treatment.…”

“…Madurella mycetomatis, M. fahalii, M. tropicana and M. pseudomycetomatis are indistinguishable by culture 23 . The few isolates from South and Central America identified by molecular techniques were found to be M. pseudomycetomatis instead of M. mycetomatis 24 . Therefore, it cannot be excluded that M. pseudomycetomatis is the dominant Madurella species in Latin‐America, 11 rather than M. mycetomatis .…”

“…23 The few isolates from South and Central America identified by molecular techniques were found to be M. pseudomycetomatis instead of M. mycetomatis. 24 Therefore, it cannot be excluded that M. pseudomycetomatis is the dominant Madurella species in Latin-America, 11 rather than M. mycetomatis. Our specific molecular assay was able to discriminate M. pseudomycetomatis from the other Madurella species with a high degree of specificity.…”

Disseminated actinomycetoma due to Nocardia wallacei

“…Also, N. wallacei was identified in an immunocompetent 45‐year‐old Venezuelan farmer by 16S rDNA gene sequence. TMP/SMX was administered with no information regarding outcome …”