[In-vitro activity of new beta-lactam antibiotics. Testing resistant enterobacteria and pseudomonas aeruginosa strains]

The MIC's of 95 strains of enterobacteria, being resistant to Cefazolin, were determined against 8 recent beta-lactam antibiotics by the agar-dilution method. Thienamycin proved to be most active in vitro, followed by Cefotaxim, Ceftriaxon, Ceftizoxim, Ceftazidim and Monobactam; Cefoperazon and Temocillin proved to be less active. Ceftazidim showed better results with 25 strains of P. aeruginosa, including 12 strains resistent to Azlocillin, than did Cefsulodin, Piperacillin and Cefoperazon. Thienamycin showed the highest MIC's. The testing of representative antibiotics is discussed.