Comparative in vitro activities of seven new beta-lactams, alone and in combination with beta-lactamase inhibitors, against clinical isolates resistant to third generation cephalosporins.

We examined the drug susceptibility pattern of Gram-negative bacilli to seven new beta-lactams. A total of 277 non-duplicate gramnegative bacilli strains belonging to the Enterobacteriaceae family, Pseudomonas and Acinetobacter species, isolated from various clinical samples were tested for susceptibility to imipenem, piperacillin/tazobactam, cefoperazone/sulbactam, ticarcillin/clavulanate, cefdinir, cefepime and cefpirome with the disk diffusion technique. The percentage resistance was low for imipenem (7.2%), piperacillin/tazobactam (2.8%), cefoperazone/sulbactam (5.4%). However, a high frequency of resistance was observed to ticarcillin/clavulanate (83.9%), cefdinir (70.6%), cefepime (45.5%) and cefpirome (84.4%). We conclude that imipenem, piperacillin/tazobactam and cefoperazone/sulbactam are effective antibiotics in our environment, whereas ticarcillin/clavulanate, cefdinir, cefepime and cefpirome are relatively uneffective.