IDENTIFICATION AND CHARACTERIZATION OF A NOVEL DNA MARKER ASSOCIATED WITH EPIDEMIC BURKHOLDERIA-CEPACIA STRAINS RECOVERED FROM PATIENTS WITH CYSTIC-FIBROSIS

Burkholderia cepacia is a problematic pathogen that may spread among p atients with cystic fibrosis (CF), One highly infectious CF strain tha t causes epidemics in both the United Kingdom and eastern Canada has b een shown to possess both the cable pilin subunit gene (cblA) and a un ique combination of insertion sequences, However, no genetic markers l inking this strain type with other types epidemic at various centers h ave been identified, Using a randomly amplified polymorphic DNA (RAPD) typing scheme, we identified an apparently conserved 1.4-kb fragment in the DNA fingerprint of epidemic B. cepacia strains, Conservation of the DNA marker among epidemic strains was demonstrated by Southern hy bridization, and its prevalence was assessed in a collection of chromo somal DNAs extracted from 627 isolates representative of 132 RAPD-defi ned B. cepacia strain types, The marker was specifically associated wi th seven epidemic CF strains, was absent among nonepidemic strains inf ecting individual patients with CF, and rare among strains recovered f rom the natural environment, Only one of the seven epidemic CF strain types possessed DNA homologous to cblA. The RAPD marker was designated the ''B. cepacia epidemic strain marker'' (BCESM). Sequence analysis of chromosomal DNA corresponding to the 1.4-kb RAPD marker revealed th e presence of a putative open reading frame (ORF),vith significant hom ology to several negative transcriptional regulators; the ORF was desi gnated the ''epidemic strain marker regulator,'' or esmR. The BCESM DN A is the first genetic marker that has been identified to be specifica lly associated with and conserved among several epidemic B. cepacia st rains which infect multiple patients,vith CF.