DEVELOPMENT OF 2 SPECIES-SPECIFIC FINGERPRINTING PROBES FOR BROAD COMPUTER-ASSISTED EPIDEMIOLOGIC STUDIES OF CANDIDA-TROPICALIS

Candida tropicalis has emerged as the second most frequent colonizing Candida species, and it has been documented in nosocomial infections. To develop an effective fingerprinting system for this species, which is amenable to computer-assisted analyses and which provides informati on on the genetic relatedness of independent isolates, two DNA fragmen ts, Ct3 (18,000 bp) and Ct14 (20,000 bp), were cloned from a genomic l ibrary of Sau3AI partial digestion products. Both probes generate comp lex Southern blot patterns containing 8 to 20 bands, when hybridized t o EcoRI- or EcoRI-HaeIII-digested DNA of independent C. tropicalis iso lates. The two probes show no cross-hybridization and are both species specific for C. tropicalis. A comparison of the capacity of the two p robes to identify the same strain in different isolates, and different iate unrelated strains, using computer-assisted computation of similar ity coefficients and the genesis of dendrograms, suggests that while C t14 is more effective in grouping independent isolates, Ct3 is more ef fective in discriminating small differences in the patterns of highly related isolates and is therefore a more effective probe for determini ng microevolution within a clonal population and substrain shuffling i n recurrent infections. Because of their alternative attributes, it is suggested that both probes be used in fingerprinting studies of C. tr opicalis.