Figure 7.
Resistance of intracellular UPEC to antibiotic treatment. C57BL/6 mice were infected with 1 × 108 colony-forming units of the clinical cystitis isolate NU14. Six hours after infection, mice were given trimethoprim-sulfamethoxazole (54 μg/ml and 270 μg/ml, respectively) in their drinking water or were left untreated. Mice were provided fresh water with or without antibiotics daily, and at 3 days after inoculation bladders were recovered and bisected. Bladder halves were treated with either gentamicin (to kill any extracellular bacteria) or were left untreated before homogenization and determination of bacterial titers. Control experiments (not shown) demonstrated that trimethoprim-sulfamethoxazole completely inhibited the growth of NU14 in vitro.