Characterization of multiple isolates of Aspergillus fumigatus from patients: genotype, mating type and invasiveness.

The possible co-existence of different genotypes of Aspergillus fumigatus in the same case was studied in five patients colonized or infected by this opportunistic mould. A total of 22 isolates were typed by random amplified polymorphic DNA (RAPD) and microsatellite analysis. Differences in the mating type and invasiveness of the isolates were also considered. The combination of four arbitrary primers used in RAPD typing differentiated all the isolates. In microsatellite analysis, at least two different genotypes were identified in four of the five patients. The 22 isolates showed elastase activity after 10 days of incubation at 37 degrees C in an elastin-containing medium. The presence of strains of compatible mating type was observed in one of the colonized patients and one of the individuals with invasive aspergillosis. Some isolates that belonged to the same genotype in microsatellite analysis were of a different mating type. Taken together, our results suggest that multiple isolates of A. fumigatus obtained from colonized or infected patients may differ not only in their genotypes, but also in their invasiveness and mating types. Furthermore, mating type determination may be of great assistance in differentiating some isolates, as two isolates of different mating type cannot be genotypically identical.