A comparison of imipenem to ceftazidime with or without amikacin as empiric therapy in febrile neutropenic patients.

Background: Neutropenic patients with cancer are traditionally treated with empiric antibiotic combinations when they become febrile. The availability of broad-spectrum antibiotics such as ceftazidime and imipenem has made it possible to initiate therapy with a single agent (monotherapy). The objectives of this trial were to compare ceftazidime and imipenem as single agents for the therapy of febrile episodes in neutropenic patients and to ascertain whether the addition of an aminoglycoside (amikacin) to either of these agents would provide an advantage.

Methods: A prospective clinical trial was conducted in which eligible neutropenic patients with cancer were randomized to one of four treatment arms: ceftazidime alone; imipenem alone; ceftazidime plus amikacin; and imipenem plus amikacin. Efficacy analysis was done for 750 assessable episodes. A multivariate logistic-regression analysis was also performed to examine the unique contribution of various prognostic factors.

Results: The overall response rates were 76% with imipenem plus amikacin, 72% with imipenem, 71% with ceftazidime plus amikacin, and 59% with ceftazidime alone. Single-organism gram-positive infections occurred in 101 of 750 episodes. Without a change in antibiotics, the response rates were 50% with imipenem, 40% with imipenem plus amikacin, 39% with ceftazidime plus amikacin, and 38% with ceftazidime. Most responded to vancomycin or other antibiotics, and the mortality associated with gram-positive infections was only 5%. Regardless of the antibiotic regimen, the majority of uncomplicated gram-negative infections responded to therapy and the majority of complicated gram-negative infections failed to respond. Multivariate logistic-regression analysis showed that recovery of the neutrophil count was the most favorable prognostic factor in a patient's response to infection, whereas the presence of gram-positive infection, acute leukemia, pulmonary or enteric infection, and therapy with ceftazidime were unfavorable factors.

Conclusions: Single-agent therapy with imipenem is as effective as more conventional combination antibiotic therapy for the empirical treatment of febrile episodes in neutropenic patients with cancer.