USE OF MICROSATELLITE MARKERS FOR STRAIN TYPING OF MICROSPORUM CANIS

Microsatellite markers were applied in order to assess the intraspecific genetic variability of Microsporum canis, the dermatophyte more frequently associated with cat and dog. Different factors (animal species, breed, age, health state, concomitant pathologies etc.) can participate in affecting clinical presentation and outcome of M.canis infection, but the question may arise as to whether animal hosts harbor mixed genotypes of M. canis that differ in their degree of virulence and infectivity. In other words, do all lineages of M. canis have the same potential to cause different clinical forms and infect humans, or is virulence limited to a subset of isolates within a genetically diverse population? Do these genotypes differ in host predilection and pathogenicity? Methods that can discriminate between dermatophytes at strain level are expected to be useful tools to address these questions. Among the most commonly employed strain typing techniques that have evaluated dermatophyte species are those which involve the amplification of unidentified regions of the genome, relying on a pattern of bands to create a unique fingerprint for each isolate. Microsatellite markers represent a random strategy, by which to differentiate pathogen strains, that have gained in popularity owing to the highly variable nature and rapid mutability of these markers. Multi locus microsatellite typing (MLMT) has the potential to correlate specific genotypes with “phenotypical” features of interest of fungal strains. Actually, the loci under study are unlikely to be based on genes involved in virulence or other features of interest, but, due to the clonal mode of reproduction of dermatophyte fungi, genomes are transmitted to the next generation in unaltered condition and thus associated genes – such as virulence genes and microsatellite markers – are linked (Sharma et al. 2007; Graser et al. 2007). We used eight microsatellite markers in order to analyse a set of M.canis strains of animal origin. Analysis of combined dataset of the polymorphic markers allowed to detect multilocus genotypes, useful to discriminate among geographical unrelated strains. On the other hand, four strains that were recovered from different sites of a single patient (cat) and the bed of its owner yielded identical genotypes for all the loci. In other words, they identified as a single strain isolates collected from a single animal. The use of such markers on a larger collection of M.canis strains may allow to: - detect genotypes eventually linked with clinical/epidemiological features of interest (e.g particular clinical forms, infectivity for humans, host breed etc.) - determine whether multiple strains can be detected in a single patient - distinguish relapse from reinfection in patients suffering from recurrent forms - obtain tools to detect and trace sources and routes of infection and identification of contaminated spaces, thus contributing to optimize prophylaxis and hygienic regimens