Comparison between the in-vitro activity of new agents on Pseudomonas aeruginosa isolates from cystic fibrosis patients and other chronic infections.

The activities of the newer antipseudomonal agents cefsulodin, ceftazidime, U-63196, aztreonam and piperacillin were compared, together with azlocillin, carbenicillin, ticarcillin and tobramycin against 98 strains of . On all of the 43 isolates from cystic fibrosis patients and the 55 strains from other chronically infected patients, ceftazidime (MIC: 5·0 and 2·8 mg/I respectively) and cefsulodin (MIC: 8·2 and 3·1 mg/l) were the most active cephalosporins, and U-63196 the least active (MIC: 40·1 and 46·1 mg/I). A high incidence of resistance (23 of 55 strains) to tobramycin was found only in the non-cystic fibrosis isolates. The activity of the other agents was comparable in the cystic fibrosis and non-cystic fibrosis isolates. MIC for aztreonam were 15·8 and 13·6 mg/l. Piperacillin was the most active penicillin in both populations (MIC: 25·8 and 21·8 mg/l). Cross resistance was demonstrated in both populations for the penicillin compounds. [ABSTRACT FROM PUBLISHER]