Rationale for use of antimicrobial combinations in treatment of gram-negative infections. A review of recent reviews

Evaluation of aztreonam in the treatment of serious gram-negative infections in a university hospital in Saudi Arabia

The efficacy and safety of aztreonam were evaluated in an open trial at King Khalid University Hospital, Riyadh, Saudi Arabia. A total of 45 critically-ill adult patients were enrolled in the study. All patients with documented Gram-negative infection were treated with aztreonam as monotherapy. Antibiotics active against only Gram-positive and/or anaerobic organisms were allowed. Twenty cases were clinically evaluable. Eleven had lower respiratory tract infections (pneumonia), 3 had urinary tract infections, and 6 had septicemia. Clinical signs and symptoms, cultures and other laboratory profiles were assessed prior to treatment, at 4-6 days during treatment and within 2-3 days of the end of therapy (usually 7-15 days). Nineteen out of 20 (95%) had a satisfactory clinical response. All cases with septicemia and urinary tract infections were microbiologically cured. The overall microbiological response rate was 90%. Fifty-five percent of all infections were caused by Pseudomonas aeruginosa. Two patients with Gram-negative pneumonia due to P. aeruginosa did not respond microbiologically to aztreonam therapy. No serious adverse events requiring discontinuation of aztreonam therapy were reported. No mortality occurred.

Ceftazidime versus tobramycin-ticarcillin in the treatment of pneumonia and bacteremia

A prospective, randomized study was undertaken to compare the efficacy and safety of ceftazidime with those of a combination of ticarcillin and tobramycin in the treatment of 40 nonneutropenic patients with pneumonia or bacteremia. Altogether, 93% of the patients receiving ceftazidime for pneumonia were cured, and 87% of those with bacteremia responded favorably. Of the subjects who were treated with ticarcillin and tobramycin ceftazidime developed significant superinfection, and one individual treated with the aminoglycoside and carboxypenicillin developed reversible azotemia. Ceftazidime appears to be as efficacious as the ticarcillin-tobramycin combination and is probably safer with regard to oto-and nephrotoxicity; however, superinfections did occur more frequently in the group treated with ceftazidime.