DYNAMICS OF RESPIRATORY-TRACT COLONIZATION BY BRANHAMELLA-CATARRHALISIN BRONCHIECTASIS

Branhamella catarrhalis is increasingly recognized as a lower respirat ory tract pathogen, particularly in chronic lung diseases. This projec t defines a population of patients in whom the dynamics of colonizatio n and infection caused by this organism could be studied. A method emp loying pulsed field gel electrophoresis (PFGE) of genomic: DNA was dev eloped. Twenty-eight patients with bronchiectasis followed prospective ly for 26.8 mo (mean) were seen monthly or bimonthly and at the time o f a purulent exacerbation. Quantitative bacterial cultures were perfor med on sputum obtained at each visit. Six of 28 had B. catarrhalis iso lated repeatedly. Viable numbers of B. catarrhalis were similar to oth er bacterial pathogens. Restriction fragment length polymorphism (RFLP ) analysis of chromosomal DNA using PFGE was performed on 37 of the 47 isolates recovered. Each patient was colonized by two to four strains with different RFLP patterns. Duration of colonization by the same st rain was 2.3 mo (mean). Strain acquisition did not correlate with exac erbation, antibiotic therapy, or season. We conclude that (I) a subset of bronchiectatic patients is colonized with B. catarrhalis, (2) RFLP is a sensitive tool to study strain acquisition, and (3) acquisition and clearance of B. catarrhalis from the respiratory tract is a dynami c process.