DIFFERENCES IN EUKARYOTIC CELL-BINDING OF PSEUDOMONAS

The lungs of cystic fibrosis (CF) patients are frequently chronically colonized by Pseudomonas aeruginosa. Recently there has been an increa se in colonization by another pathogen Pseudomonas cepacia, which can cause a rapid decline in clinical condition or death of the patient. T he nature of the factor(s) which predispose CF patients to colonizatio n by one or both of these opportunistic pathogens is unknown. It has b een suggested that the genetic defect in CF patients results in an inc rease in the number of epithelial cell receptors available to P. aerug inosa in the lung, thus rendering CF patients more susceptible to bact erial colonization than non-CF individuals. In this study we have exam ined adherence of several strains of P. aeruginosa and P. cepacia to a variety of continuous cell lines, as well as primary cultures of CF a nd non-CF nasal polyp cells. The results suggested that there may be a decrease in the number of receptors available to both strains of Pseu domonas on cells of canine origin compared to human cells. Both strain s appear to use pill as the primary adhesin, but there is also evidenc e that non-pilus adhesins contribute significantly to eucaryotic cell binding. P. cepacia exhibited microcolony formation on all cell types, which is typical of the localized adherence pattern characteristic of the enteropathogenic Escherichia coli. However, we were unable to dem onstrate, with either P. cepacia or P. aeruginosa, a significant incre ase in adherence to CF compared to non-CF nasal polyp cultures. This f inding suggests that a factor(s), in addition to the genetic defect, p resent in the CF lung environment is(are) responsible for predisposing CF patients to chronic colonization by Pseudomonas species.