CHARACTERISTICS OF ANTIBIOTIC-RESISTANT ESCHERICHIA-COLI-0157 H7 IN WASHINGTON-STATE, 1984-1991/

The resistance of Escherichia coli O157:H7 to amoxicillin/clavulanic a cid, ampicillin, ceftazidime, ceftriaxone, cefuroxime, cephalothin, ch loramphenicol, ciprofloxacin, gentamicin, streptomycin, sulfisoxazole, tetracycline, ticarcillin, tobramycin, and trimethoprim-sulfamethoxaz ole was examined, and resistant strains were characterized. All 56 iso lates collected between 1984 and 1987 were susceptible to all antibiot ics tested; 13 (7.4%) of 176 strains isolated between 1989 and 1991 we re resistant to streptomycin, sulfisoxazole, and tetracycline. lambda- restriction fragment length polymorphism analysis suggested that the 1 3 resistant strains belonged to nine different clones. The emerging re sistance of E. coli O157:H7 to antibiotics could portend an increased prevalence of this pathogen in food animals that receive antibiotics. Antimicrobial resistance of E. coli O157:H7 could be useful as a rapid epidemiologic marker and as a way to select this pathogen from suspec ted vehicles of transmission, but this resistance could also complicat e therapeutic trials with sulfa-containing antibiotics.