[Uptake of ofloxacin by Escherichia coli]

The uptake of ofloxacin by Escherichia coli NIHJ-JC2 was determined by a sensitive and convenient method using high-performance liquid chromatography (HPLC) with a fluorometric detection (sensitivity level: 1 ng/ml). Concentrations of ofloxacin were measured in bacteria after contact with 5 micrograms/ml of antibiotic for 1, 2, 3, 5, 10, 20 and 30 min. Ofloxacin uptake was rapid, 70% of broth concentration occurring within the first min and 96% after 5 min; then it reached a plateau which was 1.16 times as high as the broth concentration.