DIFFERENTIATION OF COLONIZING AND ENVIRON MENTAL ASPERGILLUS-FUMIGATUS ISOLATES BY MOLECULAR TYPING METHODS

Purpose. Random amplified polymorphic DNA (RAPD), restriction enzyme a nalysis (REA) and Southern hybridization (SHA) with a mitochondrial DN A probe, were used in order to investigate the possible identity of 15 Aspergillus fumigatus isolates. Material and Method. These isolates w ere recovered from either a colonized patient with lung transplantatio n (n = 1), the patient's home environment (n = 13), or the clinical wa rd (n = 1) where the patient was hospitalized. In addition, 12 unrelat ed control strains were studied for comparison. Results-Conclusion. Mo lecular methods revealed high genetic biodiversity among the 27 isolat es. RAPD with primer 5 was the most discriminatory for the 12 referenc e strains and allowed to differentiate 12 types, while RAPD with prime r 2, REA and SHA generated respectively 10 types, 9 types and 6 types. While with primer 5 the RAPD pattern of the colonizing strain was dif ferent from patterns of home isolates, it was identical to the pattern of the strain recovered in the clinical ward. However, with primer 2, RAPD patterns of these two isolates were clearly differentiated. This was confirmed both by REA and SHA. Hence, the colonizing strain was d ifferentiated from isolates recovered from the close environment of th e patient and the clinical ward. This study demonstrates the need of u sing various molecular methods to conclude reliably on the identity or non-identity of A. fumigatus isolates in epidemiological studies.