Comparison of moxalactam and gentamicin in the treatment of complicated urinary tract infections.

Moxalactam and gentamicin were compared in a prospective, randomized study of 49 hospitalized patients with complicated urinary tract infections. Patients received parenteral moxalactam, 250 mg every 12 h, or gentamicin, 1 mg/kg every 8 h. The average duration of therapy (moxalactam, 7.5 days; gentamicin, 8.6 days) was similar for both groups. Sixty-two percent of patients treated with moxalactam and 57% of those receiving gentamicin were cured of their infection, as defined by a negative culture after therapy. No side effects required discontinuation of either drug. An enterococcus caused two superinfections and three reinfections in patients treated with moxalactam. Moxalactam resistance developed in Pseudomonas aeruginosa isolates from three patients treated with moxalactam. Moreover, two of these isolates showed decreased susceptibility to gentamicin, tobramycin, and amikacin. An additional 10 patients with gentamicin-resistant but moxalactam-susceptible isolates were treated with moxalactam. Forty percent of these patients were cured of their infections. Moxalactam appears to be a safe, effective drug for complicated urinary tract infections caused by susceptible bacteria, including those resistant to gentamicin. However, patients receiving moxalactam should be carefully monitored to detect enterococcal superinfections or development of resistance to moxalactam in isolates of P. aeruginosa.