Failure of excessive doses of ampicillin to prevent bacterial relapse in the treatment of acute pyelonephritis.

In order to evaluate whether very high doses of ampicillin might be more effective than conventional therapy in eradicating bacteria in patients with acute pyelonephritis, 34 affected patients were randomly assigned into two treatment groups. One group was given ampicillin in a daily dose of 30 g for three days and 20 g for four days without further treatment. The other group was given ampicillin in moderate doses for one month. Out of 13 patients treated with excessive doses for one week, only three were completely cured whereas conventional therapy cured 9 out of 21. Thus, excessive doses of ampicillin given for one week were not more effective but more expensive and possibly less beneficial than conventional therapy.