Dermatophytic onychia: Effectiveness of rapid immunochromatographic diagnostic testing directly on samples compared to culture.

BACKGROUND: Until now, definite diagnosis of dermatophytic onychia has been made by taking a nail sample and placing it in culture. The result is usually obtained only after 2 to 3weeks. More recently, diagnosis within a few minutes after sampling has become possible thanks to an immunochromatography technique developed in Japan and now available in France: the Diafactory Tinea Unguium® test strip (Biosynex, France). METHODS: Over a 12-month period, 80nail samples from 80patients giving rise to a positive fungal culture were included in the study. For each patient, part of the removed nail was stored at room temperature and an immunochromatographic test was retrospectively performed according to the supplier's instructions. A small fragment of nail (≥ 1mg) was mixed with a few drops of reagent in a tube for 1min and the test strip was then placed in the tube with the result being visible to the naked eye (control strip, positivity strip) after incubation for a few minutes. RESULTS: Compared with the culture method used for 51 isolated dermatophytes (42 Trichophyton rubrum, 9 Trichophyton interdigitale), the sensitivity of the rapid test was 96.07% (49/51). For the 29other fungal cultures (10Fusarium sp., 3Scytalidium sp., 3Scopulariopsis brevicaulis,3Aspergillus sp., 1Alternaria sp., 3Candida albicans, 1Candida parapsilosis, 1Trichosporons sp., 1Rhodotorula sp., and 3Corynebacterium sp.), the specificity was 75.86% (22/29). False positives were mainly due to the genera Fusarium and Scopulariopsis (6 of 7false positives), which were the likely cause of onychomycosis. DISCUSSION: This rapid test could be useful in limiting excessive clinical diagnosis of dermatophyte onychomycosis. The rapid test has several advantages: ease of application, speed of results, and good performance, which, together, could improve diagnostic certainty during the actual consultation, thus limiting prolonged unnecessary prescriptions of antifungal treatments, while waiting for the laboratory culture results (3weeks for a negative result).

[Scabies of the nail unit in an infant]. / Scabiose de l'appareil unguéal chez un nourrisson.

BACKGROUND: There are no guidelines regarding the management of scabies in infants and recurrence is common at this age. We report the case of an infant with subungual hyperkeratosis and ungual lesions subsequent to classic scabies. PATIENTS AND METHODS: A 7-month-girl, treated 6 weeks earlier with esdepallethrin for scabies, consulted for acquired lesions on 3 toe nails. These nails were thickened and displayed subungual hyperkeratosis. Physical examination of the skin, the finger nails and mucous membranes was otherwise normal. Fungal analyses were negative, but direct microscopic examination revealed numerous larvae of Sarcoptes scabiei as well as ovular debris. The child was treated with urea 40% to obtain chemical avulsion of the nails, and with topical esdepallethrin and a quarter tablet of ivermectin orally; there was no follow-up of the child. DISCUSSION: Ungual scabies has already been reported in crusted scabies and very rarely in classic scabies. Subungual and ungual locations of S. scabiei may constitute a source of reinfestation with scabies in infants. Treatment is not well defined and currently involves chemical avulsion of the nails and the application of topical antiscabies treatment.

[Tinea unguium with Microsporum langeronii and Trichophyton soudanense revealing tinea capitis with M. langeronii]. / Onyxis de la main à Microsporum langeronii et Trichophyton soudanense révélant une teigne du cuir chevelu à M. langeronii.

A Senegalese lady of 17 years old presented right hand tinea unguium on all fingernails except the thumb lasting for 10 years. Mycological analysis showed with the direct examination 20% KOH mount numerous septate hyphae. Culture revealed Microsporum langeronii at a first time. The mycological analysis resumption with sampling scalp revealed a tinea capitis with M. langeronii then culture of nail pieces confirmed in a second time M. langeronii also associated with Trichophyton soudanense in the tinea unguium.