The cure rate of
infections in
cancer patients is adversely affected by
neutropenia (less than 1,000/mm3). In particular, patients with severe
neutropenia (less than 100/mm3) have shown a poor response to
antibiotics. To overcome the adverse effects of
neutropenia,
tobramycin was given by continuous infusion and combined with intermittent
carbenicillin.
Tobramycin was given to a total daily dose of 300 mg/m2 and
carbenicillin was given at a dose of 5 gm every four hours. There were 125 infectious episodes in 116
cancer patients receiving myelosuppressive
chemotherapy. The overall cure rate was 70%.
Pneumonia was the most common
infection and 61% of 59 episodes were cured. Gram-negative bacilli were the most common causative organisms and 69% of these
infections were cured. The most common pathogen was Klebsiella pneumoniae and this, together with Escherichia coli and Pseudomonas aeruginosa, accounted for 74% of all gram-negative bacillary
infections. Response was not influenced by the initial neutrophil count, with a 62% cure rate for 39 episodes associated with severe
neutropenia. However, failure of the neutrophil count to increase during
therapy adversely affected response.
Azotemia was the major side effect recognized, and it occurred in 11% of episodes. Major
azotemia (serum
creatinine greater than 2.5 mg/dl or BUN greater than 50 mg/dl) occurred in only 2%.
Azotemia was not related to
duration of therapy or serum
tobramycin concentration. This
antibiotic regimen showed both therapeutic efficacy and acceptable renal toxicity for these patients.