Use of phenotypic and genotypic fingerprinting methods in the strain identification of Aspergillus fumigatus.

Aspergillus fumigatus isolates (n = 6) from a lung transplant recipient, one isolate from a patient who had been on the same ward and a reference strain (NCPF 2140) were compared using three typing methods: SDS-PAGE, immunoblotting with serum from the transplant patient and random amplified polymorphic DNA (RAPD) assay. Neither the SDS-PAGE, immunoblot nor RAPD assay with single primers revealed differences between the eight isolates. Digestion of one primer product with the endonuclease EcoRI discriminated between the six patient isolates and the other two strains. The RAPD assay using pairwise combined primers showed identical patterns for the patient's strains but differentiated between the two other strains. It is concluded that any single technique may fail to detect strain differences and that a spectrum of typing methods is necessary in order to reveal or to exclude cross-infections with Aspergillus fumigatus.