1997 Volume 20 Issue 5 Pages 584-585
We evaluated the antimicrobial sesceptibility to six strains of Escherichia coli O157 (E. coli O157) isolated from patients in Yamaguchi Prefecture between June and July, 1996. Seven antimicrobial agents that were expected to retain a high concentration in the intestine were selected. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of ciprofloxacin, polymyxin B, cefoperazone, and kanamycin for each strain were ≤6.25 μg/ml. However, the MIC of fosfomycin was 3.13-100 μg/ml, and its MBC was ≥100 μg/ml. The MIC of ampicillin and tetracycline was >100 μg/ml in some strains. In a time-kill study of E. coli O157 at a drug concentration of 12.5 μg/ml, about 104 colony forming units/ml of E. coli O157 were eradicated within 10 min by ciprofloxacin, within 30 min by polymyxin B, within 4 h by cefoperazone, and within 16 h by kanamycin. These results suggest that the new quinolones with a poor absorption rate in the intestine (such as ciprofloxacin and norfloxacin) are effective against E. coli O157. When oral administration is impossible, bile excreting cephem antibiotics (such as cefoperazone, cefriaxone, and cefotetan) may be useful.
