PSEUDOMONAS-AERUGINOSA CLINICAL ISOLATES - SEROTYPES, RESISTANCE PHENOTYPES AND PLASMID PROFILES

78 Pseudomonas aeruginosa strains were isolated from the respiratory t ract of 56 patients, 15 of which were affected by cystic fibrosis (CF) . The epidemiological typing scheme was based on serotyping, antibioti c resistance pattern and plasmid DNA profile, All strains (except 2 mu coid strains) were typed using a rapid slide O-agglutination technique . Most common serotypes in both group were 0:1, 0:10 and 0:6, Moreover we observed a correlation among 0:12 serotype and CF patients, Plasmi d DNA analysis showed that 45.2% (on average) of strains isolated from patients with and w/o CF harboured 1-3 plasmids ranging in size from 1 to 15 Md, Plasmid prevalence was higher in strains isolated from CF patients in specimens collected after antibiotic therapy. A correlatio n was found between 1 and 1.9 Md plasmids and resistance to aminoglyco sides. Our results indicate that the analysis of antibiotic resistance phenotypes combined with plasmid analysis may be useful, in associati on to serotyping, to characterize the circulation of P. aeruginosa str ains and the spread of resistance in these bacteria.