Objective: To characterize P. aeruginosa strains isolated from bronchoalveolar lavage fluid of cystic fibrosis (CF) patients over a 3 year period.
Material and methods: A prospective follow-up study was carried out in a population of cystic fibrosis patients. The random amplified polymorphic DNA (RAP.D) technique was used to amplify DNA of P. aeruginosa strains isolated from bronchoalveolar lavage fluid samples of five CF patients from the Servicio de Neumología y Cirugía del Tórax del Instituto Nacional de Pediatría (Mexico City Chest Clinic of the National Pediatrics Institute) in Mexico City, between June 1996 and June 2002. Amplification patterns were established for each isolate to accurately identify all strains and to carry out an epidemiological analysis of P. aeruginosa among the selected CF patients.
Results: Eighteen different DNA amplification patterns were defined and used to identify each P. aeruginosa strain isolated from the different bronchoalveolar lavage samples. No correlation was observed between the different P. aeruginosa strain genotypes and mucoid or non-mucoid phenotypes, as strains with different phenotypes showed similar amplification patterns. Several strains with different amplification patterns were identified in samples obtained from the same patient, suggesting coinfection with ore than one P. aeruginosa strain. Two siblings with CF shared similargenotypes, suggesting the occurrence of cross- contamination. Similar genotypes of P. aeruginosa strains were isolated throughout the study period.
Conclusion: Genotypic characterization of P. aeruginosa strains in CF patients allows more accurate epidemiological analyses of this important host-agent relationship.