Sensitivities of strains of enteropathogenic Escherichia coli to cephalexin and other antibiotics.

The sensitivity patterns of strains of enteropathogenic Escherichia coli to nine antibiotics were determined. Most strains were sensitive to gentamicin, kanamycin, neomycin, and colistin. Sensitivity to cephalexin was generally greater than sensitivity to ampicillin. Compared with sensitivity patterns of strains isolated in previous years, no significant change in sensitivity patterns of recently isolated strains was detected. All ampicillin-resistant strains destroyed the drug by producing beta-lactamase. The activity of this enzyme against cephalexin was significantly lower than its activity against ampicillin. The role of beta-lactamase, the correlation between its production and resistance to beta-lactamase antibiotics, and the similarity between beta-lactamase produced by EEC and the classified beta-lactamases produced by other enteric bacteria and Escherichia coli, are discussed.