Abstract :
[en] Objectives
Dermatophytosis refers to superficial fungal infections of keratinized tissues caused by keratinophilic dermatophytes. They are the most common cause of superficial fungal infections worldwide. Epidemiological studies regarding dermatophytes infections have been conducted in several countries and differences in the incidence and in etiological agents have been reported. That is why national surveillance of circulating strains causing dermatophytosis is critical. The National Reference Center (NRC) for mycoses conducted a survey on dermatophytes strains circulating in Belgium from 2012 to 2016. The present study was performed to assess the profile of dermatophytosis and to identify the species involved.
Methods
The Belgian NRC for mycoses (Leuven and Liège) collected 14227 strains between January 2012 and December 2016. The strains were obtained from clinically suspected fungal infections of skin, hair and nails. Strains were collected from Belgian laboratories in order to confirm the fungal identification which was performed by microscopy and in case of doubt by ITS sequencing.
Results
Among the 14227 samples collected, 6248 were identified as dermatophytes (44%). Trichophyton rubrum was the most prevalent species accounting for 61,3% (n=3820) of the strains collected from all sources, followed by T. mentagrophytes complex (19,2%, n=1199) according to the ancient classification (including T. interdigitale, T. benhamiae and T. mentagrophytes). Other less prevalent species were also recorded: M. audouinii (n=507, 8,1%), M. canis (n=210, 3,3%), T. tonsurans (n= 140, 2,2%), T. violaceum (n=133, 2,1%), T. soudanense (n=125, 2%), M. praecox (n=60, 0,96%) and E. floccosum (n=19, 0,3%) for the main ones. Our data show the predominance of anthropophilic species causing tinea capitis especially M. audouinii responsible for 43,4% (n=303/716) of hair/scalp infection with an increasing number from 2014 to 2016. Trichophyton soudanense, rarely observed in Belgium in the past, is an emerging agent of tinea capitis particularly since 2013, accounting for 11,3% (n=81) of the cases during the 5-year study period. Zoophilic strains such as M. canis which were well represented in the past epidemiology of tinea capitis are decreasing accounting for only 8,8% (n=63) of hair/scalp infection. Finally, our data confirm the high prevalence of T. rubrum as the main etiologic agent of onychomycosis (78,1%, n=3094/3968) followed by T. mentagrophytes complex (18,8%, n=743/3968). Both latter strains were also responsible for the majority of skin infections as they were isolated respectively in 46,2% (n=693/1612) and 21,7% (n=348/1612) of skin samples.
Conclusions
The present epidemiological survey provides recent data on the prevalence of all dermatophytes circulating in Belgium. Analyzing such data is critical for the establishment of measures for prevention and control of dermatophytes infections. Our study confirms the predominance of T. rubrum followed by species from the ancient T. mentagrophytes complex (T. interdigitale + T. benhamiae) in the Belgian population. This survey highlights also the persistent predominance of M. audouinii and the emergence of T. soudanense as causative agents of tinea capitis.
