Diagnostic implications of mycetoma derived from Madurella pseudomycetomatis isolates from Mexico

B. Nyuykonge (1) , C.H.W. Klaassen (1) , W.H.A. Zandijk (1) , G.S. de Hoog (2) , S.A. Ahmed (2, 3) , Marie Desnos-Ollivier (4, 5) , A. Verbon (1) , A. Bonifaz (6) , W.W.J. van de Sande (1)

1 Erasmus MC - Erasmus University Medical Center [Rotterdam]
2 WI - Westerdijk Fungal Biodiversity Institute [Utrecht]
3 University of Khartoum
4 Mycologie moléculaire - Molecular Mycology
5 CNRMA - Centre National de Référence Mycoses Invasives et Antifongiques - National Reference Center Invasive Mycoses & Antifungals
6 HGM - Hospital General de México Dr. Eduardo Liceaga

Background At the dermatology service of the General Hospital of Mexico City, Mexico, two patients, father and son, with black-grain mycetoma were seen. The grains were isolated, and the cultured fungi were identified as Madurella mycetomatis based on morphology. Using the M. mycetomatis specific PCR, amplicons of a different size than that of the M. mycetomatis type strain were obtained. Objective To determine the causative agent of the two black-grain mycetoma cases and develop non-culture-based diagnostic tools to identify them to the species level. Methods The M. mycetomatis specific, the internal transcribed spacer (ITS) region, β-tubulin (BT) and ribosomal binding protein 2 (RBP2) PCRs were used to confirm the identity of the isolates. Genetic variation was established by amplification fragment length polymorphisms. To determine the antifungal susceptibility profile, the Sensititre™ YeastOne™ assay was used. To develop a species-specific PCR primers were designed on the sequenced PCR amplicon from the M. mycetomatis specific PCR. Results By analyzing the ITS, BT and RBP2 regions the isolates were identified as Madurella pseudomycetomatis. The isolates from father and son were similar but not identical to M. pseudomycetomatis from Venezuela and one from an unknown origin. Madurella pseudomycetomatis isolates were inhibited by itraconazole, posaconazole and voriconazole but showed increased MIC values for amphotericin B and fluconazole. They were not inhibited by the echinocandins and five flucytosine. The two patients were treated with itraconazole resulting in cure for the father while the son was lost to follow-up. The species-specific PCR developed for M. pseudomyceotmatis was discriminative and specific. Conclusion Madurella pseudomycetomatis is genetically diverse with same susceptibility profile as M. mycetomatis and causes eumycetoma in Latin America. The M. pseudomycetomatis specific PCR can be used to identify this causative agent to the species level; however, this needs to be validated in an endemic setting.

Domaines: Mycologie

B. Nyuykonge, C.H.W. Klaassen, W.H.A. Zandijk, G.S. de Hoog, S.A. Ahmed, et al.. Diagnostic implications of mycetoma derived from Madurella pseudomycetomatis isolates from Mexico. Journal of the European Academy of Dermatology and Venereology, 2020, 34 (8), pp.1828-1834. ⟨10.1111/jdv.16402⟩. ⟨pasteur-03243532⟩