Combination of three typing methods for the molecular epidemiology of Aspergillus fumigatus infections

This study investigated the source of infection and strain relatedness of A spergillus fumigatus isolates from bronchial colonisation and invasive aspe rgillosis (IA) in four transplant patients, Environmental isolates from the patient's home and from the hospital and infecting isolates were obtained for patient A who developed LA, Clinic environmental and colonising isolate s were obtained for patient B, Sequential isolates were obtained from vario us organs from patient C who developed IA and also from patient D who had a bronchitic aspergillosis that developed into LA. Ninety-one A. fumigatus i solates were analysed by three typing methods: multi-locus enzyme electroph oresis (MLEE), random amplified polymorphic DNA (RAPD) and sequence-specifi c DNA primers (SSDP), The three combined typing methods demonstrated a grea ter differentiation of isolates than the typing methods used separately or in pairs. This demonstrated the genotypic variability of A. fumigatus and f acilitated better epidemiological analysis, Large polymorphisms were demons trated for each patient isolate between and colonies within various samples . The relatedness of the isolates suggested nosocomially acquired aspergill osis for patient B, but the source of infection for patient A remained uncl ear. The results suggested at least three multiple infections among the fou r patients. This study enabled the identification of the source of infectio n and strain relatedness, which in turn facilitates the development of prev entive measures for patient management in the future.