The first isolation in Japan of Trichophyton mentagrophytes var. erinacei causing tinea manuum

A 26‐year‐old woman with no family history of dermatophytosis presented with pruritic erythema on the right palm ( Fig. 1 ) in November 2002, 1 month after first noticing it. She had no lesions on the soles, toe webs, left palm, or nails. The erythema had been treated with topical steroids for 4 weeks, but had continued to expand. The erythema measured 42 mm × 36 mm, and was hyperemic and infiltrated unevenly. Its center showed no signs of healing, its periphery exhibited small vesicles, and its margin showed scales. On the scales, fungal hyphae and chains of arthroconidia were revealed by direct KOH test. The erythema was diagnosed as tinea manuum and was treated with topical terbinafine once daily. After several days of treatment, the erythema flared up and red papuloerythemas appeared on the back of both hands and on both forearms. Ten days after the first visit, the patient returned to our clinic for the treatment of newly developed eruptions. A trichophytin skin test produced an infiltrated erythema measuring 21 mm × 18 mm, confirming that the newly developed eruptions and exacerbated erythema on the right palm were due to a trichophytid reaction. Topical terbinafine was continued for the palm and fluocinolone acetonide ointment was applied on the newly developed eruptions on the arms from day 10 after the first visit. All the inflammatory eruptions subsided after 4 weeks of treatment and direct KOH test results were negative. Clinical finding of erythema on the right palm. The scaly erythema exhibited fine vesicles image The suspected cause of tinea manuum was the patient's pet female four‐toed hedgehog (Atelerix albiventris) which she had kept for 4 years ( Fig. 2 ). When she bought it from a local pet shop, it had desquamation on its body, but no lesions with loss of hair or quill and no dermatitis. The scaling decreased gradually with treatment given by a veterinarian. The pet four‐toed hedgehog. The species Atelerix albiventris is characterized by the four‐toed rear leg image Three isolates of dermatophytes were obtained from the scale on the woman's palm (KMU 4455), scale removed from the hedgehog (KMU 4459‐1), and a fallen‐out quill (KMU 4459‐2). KMU 4455 grew rapidly with an ivory‐white and lightly powdery surface, and with concentric ripples at the periphery. The center of the colonies was fluffy and elevated slightly, with a yellow pigment beneath ( Fig. 3 ). The strains from the hedgehog were morphologically similar to each other, and their colonies grew more slowly and had a more powdery texture than those of KMU 4455. KMU 4459‐1 and KMU 4459‐2 gave a positive urease test result, whereas KMU 4455 gave negative results even at day 7 of incubation. The microscopic findings of the three isolates were almost the same ( Fig. 4 ). Numerous teardrop‐shaped microconidia were produced along the sides of the rectangle of mycelium. Spherical microconidia clustered in some parts and some club‐shaped, 2–6‐roomed macroconidia were observed. There were some poorly developed macroconidia and some elongated microconidia which were so large that they were intermediate in size between normal microconidia and macroconidia. There was no spiral body. Gross finding of KMU 4455 isolated from the palm. A rapidly growing colony with concentric rippling at the periphery image Microscopic findings of KMU 4455. Lactophenol cotton‐blue staining. (a) Irregular‐shaped, thin‐walled macroconidia with intermediate‐sized conidia (× 600). (b) Teardrop‐shaped microconidia along the sides of the rectangle of mycelium (× 600) image The isolates were mated with (+) and (–) tester strains of African and Americano‐European races of Arthroderma benhamiae on sunflower seed agar plates. KMU 4455 produced gymnothecia with mature ascospores only when mated with the (+) strain of the African race, RV 30000 ( Fig. 5 ), whilst KMU 4459‐1 and KMU 4459‐2 produced gymnothecia only when mated with the (–) strain of the African race, RV 30001. Mating behavior on sunflower seed agar plates. (a) KMU 4455 was compatible only with RV 30000, a (+) tester strain of the African race of Arthroderma benhamiae (upper plate). (b) A high‐power view of gymnothecia produced on the upper plate image Based on the above findings, all three isolates were identified as Trichophyton mentagrophytes var. erinacei. To confirm that the isolates were not the African race of A. benhamiae, nucleotide sequence analysis of the internal transcribed spacer (ITS) regions of ribosomal DNA was performed. Total DNA was extracted from KMU 4455 and KMU 4459‐1, the ITS regions were amplified using primers ITS1 and ITS4 (White TJ, Bruns T, Taylor J. Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics. In: Innis MA, ed. PCR Protocols: A Guide to Methods and Applications. London: Academic Press, 1990: 315–322), and sequenced by a standard dye terminator method. A 591‐base pair fragment of DNA was compared with that of T. mentagrophytes var. erinacei registered in a gene database, DDBJ. The DNA fragments of KMU 4455 (DDBJ accession number AB 100263) and KMU 4459‐1 (DDBJ accession number AB 100264) were 100% homologous to those of T. mentagrophytes var. erinacei IFM 48154 (= RV28924 , DDBJ accession number AB 78899) (Takahashi Y, Haritani K, Sano A, et al. An isolate of A. benhamiae with T. mentagrophytes var. erinacei anamorph isolated from a four‐toed hedgehog (Atelerix albiventris) in Japan. Jpn J Med Mycol 2002; 43: 249–255).