[Beta-lactam-resistance patterns of some gram-negative rods].

Antibiotic susceptibility to ampicillin of 290 E. coli, 56 Klebsiella sp. And 167 P.mirabilis strains was evaluated by the disk diffusion method. Data were interpreted according to the NCCLS criteria. 37.9% of E. coli, 85.7% of Klebsiella sp. And 65.9% of P. mirabilis strains were resistant to ampicillin. In all resistant to ampicillin strains were performed resistance patterns to following antibiotics: piperacillin, amoxicillin/clavulanic acid, cefoxitin, cefuroxime, ceftazidime, cefotaxime and imipenem. The strains resistant to ampicillin were divided into four groups depending on resistance patterns.