Efficacy and safety of aztreonam-clindamycin versus tobramycin-clindamycin in the treatment of lower respiratory tract infections caused by aerobic gram-negative bacilli

Abstract

A total of 80 patients were randomized to receive either aztreonam or tobramycin for the treatment of lower respiratory tract infections caused by gram-negative bacilli; all these patients received clindamycin concomitantly. A total of 53 patients were randomized to receive aztreonam-clindamycin; of these, 46 were clinically evaluable and 39 were bacteriologically evaluable. Of the 46 clinically evaluable patients, 41 were considered cured, 3 failed to be cured, and 2 died during the study period of unrelated causes. Of the 39 bacteriologically evaluable patients, 36 were considered cured, and 3 failed to be cured. There were 26 clinically evaluable patients in the group randomized to receive tobramycin-clindamycin. Of them, 22 patients were considered cured, 3 failed to be cured, and 1 died of unrelated causes during the study period. There were 18 bacteriologically evaluable patients in the tobramycin-clindamycin group; 17 were cured, and 1 failed to be cured. The most common pathogens isolated from the patients were Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa. All of the isolated organisms were susceptible to both tested antibiotics, except for a strain of Pseudomonas cepacia resistant to both tested antimicrobial agents and a strain of Enterobacter aerogenes and one of P. aeruginosa that were resistant to aztreonam. Very few adverse reactions related to the antibiotics were seen. These effects, when present, were transient and comparable in both studied groups, except for renal-function tests, which were altered in 7.7% of the patients randomized to receive tobramycin-clindamycin and in none of the patients randomized to receive aztreonam-clindamycin. Aztreonam-clindamycin is safe and effective for the treatment of lower respiratory tract infections caused by aerobic gram-negative bacilli when the organisms are susceptible.