Invasive conidiobolomycosis has been drawing attention as an emerging mycosis with a high mortality rate. To establish a method for distinguishing conidiobolomycosis caused by Conidiobolus sp. from mucormycosis due to Rhizopus microsporus and aspergillosis caused by Aspergillus fumigatus in Formalin-Fixed Paraffin-Embedded (FFPE) tissue sections, we focused on an in situ hybridization (ISH) method targeting 18S rRNA using FFPE tissue sections from each case. Three antisense probes (probes A, B, and C) that differed in base number and sequence position were prepared separately for Conidiobolus sp., R. microsporus, and A. fumigatus using consensus primers by focusing on the hypervariable region of the V4 domain, which is particularly rich in nucleotide polymorphism among 18S rDNA. Results of ISH using the three probes for each fungus showed that by optimizing the conditions of stringency it was possible to sensitively distinguish conidiobolomycosis-causing Conidiobolus sp. from mucormyosis-causing R. microsporus, and aspergillosis-causing A. fumigatus by using probe C (Conidiobolus sp. 189 b, R. microsporus 155 b, A. fumigatus 154 b), which have mutual homology of 60% or less. This method makes it possible to quickly and reliably detect and identify these causative fungi on FFPE tissue sections, and therefore could significantly contribute to fungal disease treatment strategies.

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Animal mycoses caused by antifungal drug-resistant strains can readily be transmitted from animals to humans as a zoonosis. We report the first isolation of a terbinafine (TRBF) -resistant Microsporum canis strain from a feline dermatophytosis in Beijing. The strain exhibited TRBF minimum inhibitory concentration (MIC) of >16 μg/mL but remained susceptible to itraconazole (ITCZ)(MIC 0.023 μg/mL). We investigated the expression of the pleiotropic drug resistance (PDR1) and multidrug resistance (MDR1, MDR2, and MDR4) genes in the TRBF-resistant and TRBF-susceptible strains of Microsporum canis by Real-Time quantitative PCR (RT-qPCR) analysis. The expression of PDR1, MDR1, MDR2, and MDR4 genes was 2 to 4 times higher in the TRBF-resistant strain than in the TRBF-susceptible strains. We also isolated an azole-resistant strain of Malassezia pachydermatis from a canine Malasseziosis. The isolate exhibited an MIC of 320 μg/ml for ITCZ by broth microdilution (BM) assay, >32 μg/ml for ITCZ by E-test, and >32 μg/ml for KTCZ by E-test. We sequenced the ERG11 gene from this isolate and detected missense mutations (A412G and C905T) in the ERG11 open reading frame (ORF).

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