Resistance to beta-lactam antibiotics and ciprofloxacin in gram-negative bacilli and staphylococci isolated from blood: a European collaborative study. European Study Group on Antibiotic Resistance.

In 1987 and 1988 members of the European Study Group on Antibiotic Resistance collected 3440 consecutive isolates of Gram-negative bacilli (63%) and staphylococci (37%) from blood cultures and performed susceptibility testing by the microdilution method. The MICs of ampicillin and cefazolin for susceptible Gram-negative bacteria were 1-8 mg/l, of piperacillin less than or equal to 0.5-4 mg/l, of aztreonam, imipenem, cefotaxime and ceftazidime less than or equal to 0.125-1 mg/l and of ciprofloxacin less than or equal to 0.125-0.5 mg/l. For susceptible staphylococci the MICs of cefazolin were less than or equal to 0.5-8 mg/l, of cefotaxime 1-4 mg/l, of ceftazidime 4-16 mg/l, of imipenem and ciprofloxacin less than or equal to 0.125-1 mg/l. The antibiotic resistance rates varied between laboratories, being generally lower in northern Europe, except for imipenem, which showed uniform, low resistance rates. In Escherichia coli resistance to ampicillin, piperacillin and cefazolin could be seen to have increased since a previous survey.