Aminoglycosides do not improve the efficacy of cephalosporins for treatment of acute pyelonephritis in women

Abstract

A prospective, coordinated, randomized multicentre trial was conducted to determine whether tobramycin 160 mg intravenously (i.v.) once daily for 2 days would improve the efficacy of cefotaxime 1 g i.v. twice daily for 2 days followed by a 10-day course of oral cefadroxil 1 g twice daily, in the treatment of community-acquired acute pyelonephritis in women. Of 73 patients enrolled in the study, 51 could be evaluated according to the protocol. There were no significant differences in bacteriological cure rates between the combined treatment with tobramycin/cefotaxime and cefotaxime alone, either at short-term follow-up (63.0% vs 59.1%; 95% confidence interval (CI) for difference in proportions -23.4% to 31.2%), or up to 7 weeks after cessation of treatment (42.9% vs 52.2%; 95% CI, -18.0% to 36.6%). A modified intention-to-treat analysis showed no difference in clinical efficacy between the two regimens (68.6% vs 69.2%; 95% CI, -22.9% to 24.1%). Tobramycin seemed to enhance the resolution of inflammation by a more rapid decline in C-reactive protein levels. The high recurrence rates after treatment with beta-lactam antibiotics in this and previous studies of acute pyelonephritis may be explained by adverse ecological effects rather than failure to eradicate the infection.