Pseudomonas aeruginosa from cystic fibrosis patients: study using whole cell RAPD and antibiotic susceptibility

Pseudomonas aeruginosa is the most important bacterial pathogen in lung disease of cystic fibrosis patients. Different morphotypes of the bacterium are frequently recovered in sputum samples of these patients. We developed a whole cell Randomly Amplified Polymorphic DNA (RAPD) technique in order to establish the relatedness between morphotype, genotype and antibiotic susceptibility. Six cystic fibrosis patients already colonized by P. aeruginosa were investigated by collecting three successive sputum samples (before and after antibiotic treatment, and one month later) and selecting 10 isolates per morphotype. 250 isolates of P. aeruginosa were recovered from 16 of 18 sputum samples. Five patients carried a single RAPD type strain four of which showed at least two morphotypes; one patient carried two RAPD types strains. No patients carried the same strain. These results confirmed other studies previously published in showing stability of the chronic colonization with a single strain. Antibiotype differences were not associated with differences of RAPD profiles and no relation was found between antibiotype and morphotype.