Aerobic and facultative Gram-negative bacilli are tested susceptibility by using MIC of imipenem, ertapenem, cefepime, cefepime+clavulanate, ceftazidime, ceftazidime+clavulanate, cefoxitin, ciprofloxacin, amikacin, levofloxacin, cefotaxime + clavulanate, cefotaxime, piperacillin + tazobactam, ampicillin + sulbactam, and ceftriaxone with MicroScan microplates.