Prise en charge des onychomycoses

Onychomycosis

Onychomycosis is a fungal infection of the nail, and the most common nail infection worldwide, causing discoloration and thickening of the nail plate. It is predominantly caused by dermatophytes. Clinical presentation is polymorphous. Diagnosis must be confirmed by mycological examination before initiating any therapy. Management is an ongoing challenge, often requiring several months' treatment, with a high risk of recurrence. Treatment must be adapted to clinical presentation and severity and to the patient's history and wishes. Debridement of all infected keratin is the first step, reducing fungal load. Systemic treatments are more effective than topical treatments, and combining the two increases the cure rate. Terbinafine is the drug of choice for dermatophyte onychomycosis, due to low drug interaction and good cost-effectiveness. Itraconazole and fluconazole are broad-spectrum antifungals that are effective against dermatophytes, yeasts, and some non-dermatophytic molds. Recurrence rates for onychomycosis are high. Prophylactic application of topicals and avoiding walking barefoot in public places may help prevent recurence.

Direct examination, histopathology and fungal culture for the diagnosis of onychomycosis: A retrospective, comparative study on 2245 specimens

BACKGROUND

Onychomycosis affects 5.5% of the general population and represents up to 50% of all nail diseases. Diagnosis and pathogen identification are essential in order to plan an adequate treatment. Many diagnostic techniques are available, and however, no solid data regarding comparison between different techniques over a large number of specimens are available to date.

OBJECTIVES

To compare sensitivity and specificity of direct examination, histopathology and fungal culture in our referral mycology laboratory.

METHODS

Nail specimens received at the cutaneous pathology and mycology laboratory of the University Hospital Saint-Pierre (Brussels, Belgium) between 1 January and 15 May 2018 were retrospectively analysed. All specimens were submitted to direct examination and culture. In cases of adequate specimen size, histopathology was performed. Fungal culture was considered the gold standard for diagnosis.

RESULTS

A total of 2245 nail samples were included in the study. Onychomycosis was diagnosed in 1266 specimens. Sensitivity and positive predictive value were found to be higher for direct examination compared to histopathology, while sensitivity of direct examination was found to be lower. Combined approach with all the three techniques showed the highest rate of positivity, followed by the association of direct examination and histopathology.

CONCLUSIONS

To our knowledge, this study included the largest number of nail specimens to date, allowing a comparison between direct examination, culture and histopathology. Direct examination showed to be the most performing technique in routine practice. Histopathology represents the most effective option in cases where both specimen size and laboratory resources are adequate. Our paper adds to the literature the 'real-life' experience of the mycology laboratory of a referral centre for nail diseases.

THE PREVALENCE OF ONYCHOMYCOSIS IN THE ZAGREB AREA - THE ROLE OF SABOURAUD AGAR WITHOUT CYCLOHEXIMIDE IN DIAGNOSIS AND THERAPY

SUMMARY – Mycological analysis is considered the gold standard in the diagnosis of very common fungal diseases of nails. The purpose of the article is to present the prevalence of onychomycosis obtained by using direct microscopic examination (DME) and cultivation on Sabouraud media without cycloheximide. The quantitative retrospective research was conducted on 2706 patients of both sexes (mostly middle-aged to elderly) with various toenail lesions, who had undergone mycological analyses in the Mycological Laboratory of our Department of Dermatovenereology in 2013 and 2014. Analysis of the results obtained revealed that there were 35.4% of positive DME results; of these, there were 39.2% of dermatophytes, 59.1% of yeasts and 1.7% of molds. The percentage of dermatophytes (Trichophyton spp.) was twice as high in men as in women. A considerable percentage (12%) of mixed isolates was also observed. Particularly worrisome was the high percentage (one-third) of suppressed and insufficiently developed dermatophytes (a possible indicator of inappropriate preparation of patients for mycological analysis). Cultivation on culture media without cycloheximide requires frequent inspections because of the fast-growing molds while not allowing sporulation for a great number of dermatophytes. However, it has certain advantages, i.e. it offers an insight into the wide range of the present fungi. As part of the biofilm, they can be potentially pathogenic in dystrophic nails under certain circumstances because, according to our results, the percentage of dermatophytes does not change substantially with aging; however, what does change is the percentage of molds, yeasts and mixed isolates.