Background: The improved efficacy of imipenem over other beta-lactam antibiotics in the treatment of febrile neutropenic patients has been attributed to its broad spectrum of activity.
Methods: A prospective, randomized, clinical trial was performed comparing vancomycin 1 g every 12 hours plus imipenem/cilassatin 500 mg every 6 hours and the same dose of vancomycin plus aztreonam 2 g every 6 hours for empiric treatment of febrile episodes in neutropenic patients with cancer.
Results: The imipenem regimen cured 76% of the 148 evaluable episodes compared with a 67% cure rate for the 152 episodes treated with the aztreonam regimen (p = 0.1). Most of the polymicrobial infections (77% or 10/13) treated with the imipenem responded, whereas only 38% (5/13) of these infections responded to the aztreonam regimen. Although the cost of the imipenem regimen was less than the cost of the aztreonam regimen, it was associated significantly more with skin rashes (12/194 vs 3/189, p = 0.02). In a multivariate analysis, a poor outcome was independently associated in both instances with the persistence of neutropenia and the presence of pneumonia (p < 0.001).
Conclusions: Overall, in a multifactorial analysis that included efficacy, toxicity, and cost, the imipenem and aztreonam regimens were comparable.