Naive tinea corporis et cruris in an Immunocompetent adult caused by a geophile Nannizzia gypsea susceptible to Terbinafine - Rarity in the current scenario of Dermatophytosis in India

Abstract

Introduction: Dermatophytosis caused by Nannizzia gypsea formerly Microsporum gypse um is rare in occurrence due to its geophilic adaptation and weak pathogenic potential in establishing infection in humans. The taxonomical status of N. gypsea has been controversial over the years and has now reached a concordance among mycologists. Innumerable reports of N. gypsea causing widespread infection in human immunodeficiency virus patients trails them as an important agent of consideration in an immunocompromised host. There have been sporadic reports of N. gypsea causing glabrous skin tinea and onychomycosis in healthy patients and the prevalence reports gravitate around 1-6.5 %. A variety of non-anthropophilic dermatophytes including novel species have now been implicated in causing dermatophytosis reflecting the era of crux changes in the epidemiology.

Case report: We present a case of chronic dermatophytosis in a 22-year-old healthy Indian with a history of contact with a dog and soil and other factors favouring dermatophytosis. Conventional and molecular sequencing established the isolate as N. gypsea. Antifungal susceptibility test revealed a higher MIC of griseofulvin and lower MIC to azoles and terbinafine. The patient had complete clinical resolution following administration of oral terbinafine.

Conclusion: Amidst the hyper-endemic-like scenario of tinea in India, this case report stands as a unique example of a patient infected with N. gypsea showing complete clinical resolution using terbinafine. Studies implicating N. gypsea in an immunocompetent host are rare and there is a need for more studies on geophilic dermatophytes causing tinea in the man for laying down effective preventive measures.

Keywords: CLSI M38A2; ITS sequencing; Nannizzia gypsea; geophile; immunocompetent host; terbinafine; tinea corporis et cruris.

Fig. 1.

Description of lesions of Tinea in an immunocompetent Indian male. (a) Circinate scaly plaques with a well-defined erythematous scaly plaque of size 5x6 cm with papules in the border on the flexor aspect of the right forearm (arrowhead); (b) Erythematous irregular scaly plaques over the lower part of the lower leg of size 2x2 cm (arrowhead).

Fig. 2.

Direct microscopy and fungal culture of the skin scrapings. (a) Direct 20 % KOH preparation of the skin scrapings (40X) showing thin hyaline septate hyphae characteristic of dermatophytes (arrowhead). (b) Growth on SDA with chloramphenicol and cycloheximide showing powdery growth (arrowhead). (c) Growth on DTM with Dermato Supplement changing pH (arrowhead) of the media. (d) Subculture on PDA after 2 weeks showing powdery surface texture with buff or brownish colour and peripheral fringe of a white zone (arrowhead). (e) Reddish reverse on PDA (arrowhead).

Fig. 3.

Physiological and morphological features of the isolate. (a) Perforating organs on sterile pre-pubescent hair in vitro (arrowhead). (b) Powdery growth with brownish pigment on sterile polished rice grain inoculation (arrowhead). (c) Hydrolysis of Christensen’s urea medium with 10 days of inoculation (arrowhead). (d, e) Lacto phenol cotton blue (LPCB) mount showing a moderate number of teardrop shaped microconidia (arrowheads), measuring 2–3×5–8 µm smooth walled and are borne laterally on the septate hyphae, arranged in solitary and small groups were seen. Numerous spindle-shaped macroconidia (arrowheads), thin-walled and echinulate surface (arrowheads) with 4–6 septa (arrowheads) and measuring 150×15 µm (arrowhead) and a few of them showing blunt tips (arrowhead).

Fig. 4.

Follow-up of tinea owing to N. gypsea after successful terbinafine regimen. Complete resolution of tinea caused by N. gypsea on the flexor aspect (a) of the right forearm, lower leg (b), and the lower abdomen (c) and other sites after terbinafine therapy without any residual scar or relapse at the follow-up of 1-year duration.