Representative isolates of nonmucoid Pseudomonas aeruginosa were studied to investigate the hypothesis that mucinophilic and chemotactic properties in this species act as potential factors in the initial stages of pulmonary colonization in patients with cystic fibrosis (CF). Transmission electron microscopy with a surfactant monolayer technique was used in a novel manner to demonstrate the adhesion of all 10 P. aeruginosa strains examined to porcine gastric mucin and tracheobronchial mucin from a patient with CF. Control experiments showed that Escherichia coli K-12 and single representatives of Proteus mirabilis and KlebsieUa aerogenes did not bind to these mucins. The Adler capillary technique, used to measure bacterial chemotactic response, showed that purified CF mucin acted as a chemoattractant for most P. aeruginosa strains, with the exception of the nonmotile mutant M2Flaand the nonchemotactic mutant WR-5. The ability of the major sugar and amino acid components of mucin to act as chemoattractants was investigated. The degree of chemotaxis was strain specific; optimum chemotaxis was observed toward serine, alanine, glycine, proline, and threonine. No strain showed chemotaxis to N-acetylneuraminic acid, but all strains showed a strain-dependent chemotactic response to the sugars L-fucose, D-galactose, N-acetyl-D-galactosamine, and N-acetyl-D-glucosamine. These results provide new information on the mucinophilic and chemotactic properties of nonmucoid P. aeruginosa and support the hypothesis that these properties could play a role in the initial stages of pulmonary colonization in patients with CF.

Summary.We sought evidence to determine if particular strains of Pseudomonas aeruginosa have a predilection for pulmonary colonisation in patients with cystic fibrosis (CF). The incidence of common pyocin types in non-CF isolates (74%) was similar to that noted in previous reports but differed significantly (x2 = 16.7, p < 0.001) from the incidence of 40% observed in CF isolates. A retrospective analysis of respiratory isolates also indicated a relatively low incidence of common pyocin types (44%) in isolates from non-CF patients with chronic airways diseases and this incidence also differed significantly from that observed (73%) in other respiratory isolates from patients in the same hospital. These observations suggest that a subpopulation of P . aeruginosa exists which has a predilection for pulmonary colonisation in CF and other chronic pulmonary diseases and may assist in identification of factors affecting bacterial colonisation.