GENOME FINGERPRINTING AS A TYPING METHOD USED ON POLYAGGLUTINABLE PSEUDOMONAS-AERUGINOSA ISOLATES FROM CYSTIC-FIBROSIS PATIENTS

Phenotypical changes occur in the surface of Pseudomonas aeruginosa during the chronic lung infection of cystic fibrosis patients. It is difficult with the classical typing methods, such as serotyping, phage typing and pyocin typing, to decide if a patient has been colonized with a new strain or whether it is the same strain which has reappeared, for instance after chemotherapy in the lungs. This investigation was carried out to evaluate genome fingerprinting as a typing method and to see how it correlated with classical methods and with DNA probe typing. Forty Pseudomonas aeruginosa isolates, 34 polyagglutinable and six monoagglutinable, from 14 cystic fibrosis patients were analysed using genome fingerprinting. The bacterial chromosomes were digested with the restriction endonucleases Dra 1 and Xbal, and separated by field inversion gel electrophoresis. The results were compared with those of a previous work (Ojeniyi et al. 1990) concerning typing with a DNA probe, serotyping using both polyclonal and monoclonal sera, phage typing, pyocin typing and reverse phage typing. The results of genome fingerprinting and DNA probe typing showed the best correlation, followed by pyocin typing. The correlation between the results of genome typing and the other typing methods was low. The discriminatory effect of genome fingerprinting was higher than that of DNA probe typing, and genome fingerprinting was found to be the best single method for epidemiological investigations of polyagglutinable isolates from cystic fibrosis patients.