Cutaneous murine model of infection caused by Neoscytalidium dimidiatum: a preliminary study of an emerging human pathogen

Abstract

Neoscytalidium dimidiatum is an emerging fungus that causes a skin infection similar to dermatophytosis; it affects both immunocompetent and immunosuppressed individuals, and it may invade deeper tissues and organs and cause systemic disease. Little is known about the etiopathogenesis of the infection caused by this fungus, and no standard effective treatment is available. The aim of the present experimental study was to develop an animal model of skin infection with N. dimidiatum. BALB/c mice were inoculated with two fungal strains, and different routes of infection were tested. When challenged intradermally, N. dimidiatum strain HUPE164165 caused skin infection in 67% of the animals whereas strain HUPE115669 did it in 49%. Neoscytalidium dimidiatum was isolated from the skin of 25% of the animals inoculated via epidermal scarification and from 100% of the animals challenged via subcutaneous injection. Mice inoculated intradermally were followed-up during four weeks, and clinical samples were collected on days 3, 8, 15, and 29 after inoculation, corresponding to different stages of infection. The cutaneous infection rate, as measured by the recovery of N. dimidiatum strain HUPE164165 from skin biopsies of animals inoculated intradermally, revealed the presence of infection in 90% of the animals sacrificed at 3 days post-inoculation, 71% at 8, 85% at 15, and 33% at 29. Conidia and hyphae were observed in PAS-stained sections as well as a mild to moderate inflammatory infiltrate in haematoxylin-eosin, although it did not differ from animals inoculated either with T. quinckeanum or PBS. The intradermal route of inoculation was considered to be suitable for the study of skin infection with N. dimidiatum The animal model developed in this preliminary study is the first to allow the study of cutaneous infection with N. dimidiatum and may contribute to further investigations of the aetiology, immunology, pathogenesis and treatment targeting this emerging mycosis.

Assessing the causes and consequences of gut mycobiome variation in a wild population of the Seychelles warbler

“…High MHC diversity was associated with a reduction in the abundance of an ASV in the fungal family Botryosphaeriaceae . Members of the Botryosphaeriaceae have predominantly been found in association with plants, often as pathogens [ 133 ], but certain genera can cause opportunistic infections in animal species [ 134 ]. Thus, it is possible that this species was more likely to be detected and selectively eliminated from the GM of individuals carrying a greater repertoire of MHC-I motifs.…”

Identification and biofilm development by a new fungal keratitis aetiologic agent

“…In recent years, reports have appeared documenting the ability of N . dimidiatum to infect mammals, especially humans . In general, human infections by Neoscytalidium could be disseminated, subcutaneous and cutaneous, with the latter occurring more frequently in tropical and subtropical countries.…”

“…However, Neoscytalidium dimidiatum, while not a frequent human pathogen, is able to generate phaeohyphomycosis, which may be manifested as disseminated infections or as subcutaneous and cutaneous infections (cerebral and pulmonary infections, atrial fungal endocarditis, mycetoma, onicomicosis). In some cases, these infections have been fatal . Neoscytalidium keratitis is rare although some instances of the infection have been documented…”

Superficial black onychomycosis due to Neoscytalidium dimidiatum

“…9 The latter is considered an emerging fungus of the dematiaceous family, which causes chronic cutaneous and nail lesions, and may even invade deeper tissues. 10 This report describes a case of superficial black onychomycosis caused by Neoscytalidium dimidiatum, demonstrating the importance of including this organism in the differential diagnosis for pigmented nail lesions that can mimic melanoma. Simple semiological and complementary methods can support or confirm the diagnosis of black onychomycosis.…”