[N-formimidoyl-thienamycin: in Vitro Activity in Bacteria with Resistance to Beta-lactam Antibiotics or Gentamicin]

The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of N-formimidoyl-thienamycin were determined for 25 strains each of Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Serratia marcescens and Pseudomonas aeruginosa which were resistant to gentamicin and/or acylureido penicillins or cefotaxime, cefoperazone or moxalactam, and for 38 strains of the group D streptococci. The drug was very active against the most frequently encountered gram-negative resistant causative organisms of nosocomial infections. The MIC ranged from 0.25-1 mg/l for multiresistant Enterobacteriaceae, and from 0.5-4 mg/l for multiresistant P. aeruginosa. The group D streptococci (enterococci) showed a low MIC (median: 0.75 mg/l); the median of the MBC was greater than 64 mg/l, however.