Comparison of amikacin and tobramycin in the treatment of infection in patients with cancer.

Two new aminoglycoside antibiotics, tobramycin and amikacin, were compared in a randomized study of the treatment of infections in patients with cancer. For the identified infections, the response rate for tobramycin was 60% and for amikacin was 64%. Pneumonia, urinary tract infection, and septicemia were the most frequent infections. Most (78%) of the identified pathogens were gram-negative bacilli; Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa were the most frequently isolated organisms. When only infections due to gram-negative bacilli were considered, 67% responded to tobramycin and 69% responded to amikacin. All infections except pneumonias had at least a 50% response rate to either antibiotic. The major form of toxicity of both antibiotics was azotemia and occurred in 22% of cases treated with tobramycin and in 20% treated with amikacin. Tobramycin and amikacin are equally effective in the treatment of gram-negative infections and have similar toxicity.