Pseudomonas aeruginosa and beta-lactams resistance phenotypes

ABSTRACT

366 strains of P. aeruginosa were studied. More than half of samples were issued from urology [40%] and general surgery [21%] and samples are mostly urine specimens [46%]. The phenotypes of resistance to 3 beta-lactams [respectively ticarcillin, cefotaxime and ceftazidime] showed that 73% of the strains were wild phenotype [SSS-SIS-SRS]. The MIC of ticarcillin +/- clavulonic acid, azlocillin, cefoperazone, cefsulodin, cefotaxime and ceftazidime against 93 strains chosen among different phenotypes of resistance showed that ceftazidime is the most active beta-lactam, 93% of strains being inhibited by 16 micro g/ml. These MIC and iodometric test performed on 33 strains with ticarcillin MIC > 128 mg/l showed that acquired resistance was non enzymatic in 21% of cases and was related to beta-lactamase production in 79% of cases