Abstract
Aspergillus species are widely distributed fungi that release large amounts of airborne conidia that are dispersed in the environment. Aspergillus fumigatus is the species most frequently isolated from human infections. In this thesis a novel assay for fingerprinting A. fumigatus is described and evaluated. This assay demonstrate several characteristics important for a good typing assay. Of major importance was the ability to discriminate between unrelated isolates. Typing results from epidemiological related collections showed identical genotypes and the results are in concordance with other high discriminatory typing techniques. Other advantages include the requirement of low amounts of DNA, and the automated sizing of amplification products result in the relatively easy interpretation of the data. The STRAf assay is also rapid and has a high throughput by multiplexing. The assay is robust, which makes it possible to successfully use the assay in other settings. Together with the use of allelic ladders it is even possible to exchange fingerprint typing data between laboratories, provided that they have access to high resolution electrophoresis platforms. In CF patients different colonization patterns were found with the STRAf assay. In IA patients the uniqueness of clinical isolate and the dissemination route are evaluated. With the option to genotype A. fumigatus directly in FFPE-tissue samples and serum samples, it is possible to retrospectively examine dissemination routes in IA patients without A. fumigatus cultures. In outbreak settings, where besides clinical isolates also environmental isolates were analyzed, variations in a single loci between epidemiological related isolates were found. The knowledge of the rate of change of the individual markers of the STRAf assay, may provide good guidelines for the interpretation of different STRAf typing patterns. The high throughput of samples, the low costs, the robustness and the interlaboratory reproducibility together with the high discrimination power makes this assay suitable for fingerprinting large amount of isolates and exchange of results between labs worldwide
