GENOME MACRORESTRICTION ANALYSIS OF SEQUENTIAL PSEUDOMONAS-AERUGINOSAISOLATES FROM BRONCHIECTASIS PATIENTS WITHOUT CYSTIC-FIBROSIS

The respiratory tracts of bronchiectasis patients may be persistently colonized with Pseudomonas, aeruginosa, despite intensive chemotherapy . The organism may undergo phenotypic changes in these patients, provi ding misleading typing results by conventional methods. We prospective ly studied eight bronchiectasis patients without cystic fibrosis over a period of 1 year. A high microbial load of P. aeruginosa was found i n 70% of sputum samples collected. Of these, 55 sequential P. aerugino sa isolates were characterized by a genotyping method, pulsed-field ge l electrophoresis, to overcome the problem of differentiating the P. a eruginosa strains during chemotherapy. Genome macrorestriction fingerp rinting patterns were analyzed after digestion with XbaI restriction e ndonuclease. Of the eight patients, six harbored a single dominant str ain of P. aeruginosa, with an intrapatient macrorestriction similarity pattern range of 96 to 100%. The other two patients were infected wit h mixed bacterial isolates including P. aeruginosa. However, diversity was observed in the P. aeruginosa isolates from all eight patients, w ith a relatedness of only 55 to 65%. The study further strengthens the fact that pulsed-field gel electrophoresis can be used efficiently an d effectively to differentiate P. aeruginosa strains in bronchiectasis patients without cystic fibrosis.