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).

[Contribution of Trichrome Blue in the diagnosis of microsporidiosis]. / Apport du trichrome bleu dans le diagnostic des microsporidioses.

Detection of microsporidia belongs to the usual coprologic and urine detection of parasites from HIV seropositive patients. To improve the identification of microsporidial spores, several stains have been used. Trichrome Blue stain has been evaluated in this study. We first compared Trichrome Blue stain to Weber's trichrome for the detection of microsporidia in smears of stools received from HIV seropositive patients. No difference of sensibility has been demonstrated between the two stains, and Uvitex 2B used on the same samples has confirmed these results. Then, Trichrome Blue stain has been used for the detection of microsporidial spores in other specimens (40 samples of nasal mucus, conjonctival samples, duodenal biopsy and urine), also Giemsa and Uvitex 2B. The advantage of Trichrome Blue stain is its ready-to-use presentation, and faster realisation at higher temperature. Trichrome Blue stain is interesting as a confirmation technique or for laboratories which do not have fluorescent microscopy equipment.

In vitro model to assess effect of antimicrobial agents on Encephalitozoon cuniculi.

We have developed a new micromethod to study the effect of drugs on microsporidia, using MRC5 fibroblasts infected by 10(5) spores of Encephalitozoon cuniculi. After 3 days of incubation with various concentrations of drugs, parasitic foci were counted in stained cultures. The inhibition of microsporidial growth exceeding 90% with albendazole (0.005 microgram/ml), fumagillin (0.001 microgram/ml), 5-fluorouracil (3 micrograms/ml), and sparfloxacin (30 micrograms/ml) was observed. Chloroquine, pefloxacin, azithromycin, and rifabutin were partially effective, at high concentrations. Arprinocid, metronidazole, minocycline, doxycycline, itraconazole, and difluoromethylornithine were not evaluable, since concentrations that inhibited microsporidia were also toxic for fibroblasts. Pyrimethamine, piritrexim, sulfonamides, paromomycin, roxithromycin, atovaquone, and flucytosine were ineffective. Our results confirm that albendazole and fumagillin have marked activity against E. cuniculi and show the antimicrosporidial activity of 5-fluorouracil and sparfloxacin. These data may form the basis for treatment of Encephalitozoon hellem and Septata intestinalis infections and represent an attempt to identify drugs effective against Enterocytozoon bieneusi.