Beta-lactam antibiotics alone or in combination with gentamicin for therapy of gram-negative bacillary infections in neutropenic patients.

This study was initiated to determine whether antibiotic combinations are superior to single antibiotics for the treatment of gram-negative bacillary infections in neutropenic patients. Twenty-six patients with Pseudomonas and Proteus infections received either carbenicillin or carbenicillin, plus gentamicin. The cure rates were 83 and 93 per cent, respectively. Twenty-three patients with infections caused by other gram-negative bacilli received either cephalothin plus gentamicin. The cure rates were 64 and 67 per cent, respectively. Superinfection occurred in 26 per cent of the patients who received a single antibiotic compared to 15 per cent of the patients who received a combination. Four of the 26 patients who received gentamicin developed transient azotemia. Combination therapy may be superior to single antibiotic therapy, but this study demonstrated no statistically significant differences.