A comparative study of ticarcillin plus tobramycin versus carbenicillin plus gentamicin for the treatment of serious infections due to gram-negative bacilli.

The combination of ticarcillin plus tobramycin (TT) or carbenicillin plus gentamicin (CG) was used to treat 82 patients with severe systemic gram-negative infection in a prospective, randomized study. Pseudomonas aeruginosa was the primary pathogen in 7 (93 per cent) of these patients. Patients treated with TT responded more frequently (92 per cent or 37 of 40) than patients treated with CG (71 per cent or 30 of 42) (p is less than 0.05). This difference was primarily due to a greater response to TT in patients with pulmonary infections (93 per cent versus 68 per cent) and infections due to Pseudomonas (92 per cent versus 70 per cent). Severity of underlying disease was also an important determinant of response. Except for a greater incidence of hepatotoxicity with CG (23 per cent versus 3 per cent; p is less than 0.02), there was no difference in toxicity, colonization with drug-resistant microorganisms or superinfection between the two treatment groups. The combination of TT appears to be superior to CG for the treatment of pulmonary infections due to Pseudomonas aeruginosa.