The role of antibiotic tolerance in the response to treatment of pyelonephritis due to Staphylococcus aureus in rats.

The effect of tolerance to methicillin on the response to treatment of hematogenous pyelonephritis due to Staphylococcus aureus was evaluated in rats. Tolerance was defined as a ratio of minimal bactericidal concentration to minimal inhibitory concentration of greater than or equal to 32. Rats that were infected with tolerant or nontolerant stains of S. aureus were treated with methicillin with equal success as judged by the number of bacteria in the kidneys and the proportion of rats with infected kidneys. In this animal model, tolerance does not play a role in the outcome of treatment.