COMPARISON OF 4 DNA-BASED METHODS FOR STRAIN DELINEATION OF CANDIDA-LUSITANIAE

Four methods for the accurate delineation of epidemiologically related and unrelated strains of Candida lusitaniae were compared, Three puls ed-field electrophoretic methods, including two contour-clamped homoge neous field gel electrophoresis methods (EKP-1 and EKP-2) yielding ele ctrophoretic karyotype patterns of intact chromosomal DNA and a method in which the chromosomal DNA was macrodigested with the endonuclease SfiI prior to pulsed-field electrophoresis (MDP), and a random amplifi ed polymorphic DNA (RAPD) assay were evaluated, A selected panel of 21 well-characterized isolates representing 13 strains of C. lusitaniae, including 7 epidemiologically related isolates of one strain (group I -A), 3 epidemiologically related isolates of another strain (group I-B ), and 11 epidemiologically unrelated isolates (group II), were tested , All isolates were coded and tested in a blinded manner, All seven gr oup I-A isolates were confirmed to be a single strain by the EKP-1 and MDP methods, and the three group I-B isolates were shown to de a sing le strain by the EKP-1, EKP-2, MDP, and RAPD methods, Subtle differenc es were noted with two of the group I-A isolates by the EKP-2 method, whereas three of these isolates were different by the RAPD method, Eac h group II isolate had distinct patterns by all four methods, These da ta support the fact that the three pulsed-field electrophoretic method s and the RAPD) method can be used to delineate strains of C. lusitani ae. The EKP-1, EKP-2, and MDP gave results that correlated with the ep idemiologic characteristics of the isolates tested in the study, where as the RAPD method was perhaps too sensitive in detecting DNA changes for epidemiologic studies.