Search

Sixty-two patients who had postpartum endometritis were treated with clindamycin in combination with either aztreonam or the aminoglycoside gentamicin. Currently, the combination of clindamycin and an aminoglycoside constitutes a treatment of choice for this condition. Our results suggest that aztreonam can be substituted for an aminoglycoside in the treatment of postpartum endometritis with similar clinical outcomes.

The in vitro susceptibility of 103 well-characterized strains of Pseudomonas aeruginosa to nine antimicrobial agents was assessed by means of the Kirby-Bauer disk diffusion assay and the microtiter minimal inhibitory concentration assay. The antimicrobials, from the most to the least active against P aeruginosa, were thienamycin greater than ceftazidime greater than piperacillin greater than azlocillin greater than cefoperazone greater than aztreonam greater than ticarcillin greater than ticarcillin-clavulanic acid greater than mezlocillin. The resistance patterns of the antimicrobial agents suggest that P aeruginosa resistant to a penicillin, cephalosporin, or aztreonam may be susceptible to thienamycin.

Twenty-seven Escherichia coli test strains that were not susceptible to cephalothin were tested for susceptibility to cefazolin, cefamandole, and ceforanide. By zone-size criteria (greater than or equal to 18 mm), 67% of E coli were susceptible to cefazolin and cefamandole, and 93% were susceptible to ceforanide. By microtiter assay (MIC less than or equal to 8 micrograms/ml), 88% were susceptible to cefazolin and cefamandole, and 94% were susceptible to ceforanide. The results support susceptibility testing of E coli with specific first- or second-generation cephalosporins rather than with class agents.

The effects of amikacin in combination with aztreonam were tested on 100 strains of gram-negative bacteria by means of the microtiter checkerboard system. Eighty-one strains were Pseudomonas aeruginosa, eight were Enterobacter species, seven were Acinetobacter species, two were Alcaligenes species, one was a Citrobacter organism, and one was Pseudomonas stutzeri. All strains had a minimal inhibitory concentration (MIC) to aztreonam between 4 and 256 micrograms/ml (MIC50 = 16 micrograms/ml) and an MIC to amikacin between 8 and greater than 128 micrograms/ml (MIC50 = 16 micrograms/ml). A synergistic effect (fourfold less MIC when both aztreonam and amikacin were present) was observed for 40 (49%) of 81 P aeruginosa and three (16%) of 19 of the other strains tested. All the remaining test strains showed an additive response; no antagonism was observed. The MICs to aztreonam and to amikacin for 98% of strains that exhibited synergism ranged from 2 to 32 micrograms/ml.

Seventy hospitalized patients with upper urinary tract infections were treated with cefoperazone (2 gm) and sulbactam (1 gm) every 12 hours for three or more days. All but six patients also received vitamin K. Forty of the 70 patients (57%) were cured of infection at one week after treatment, 13 relapsed, 11 had reinfections, and six were lost to follow-up. There were no treatment failures. Escherichia coli was the predominant pathogen (62% of isolates). Overall there was 15% resistance to cefoperazone and all resistant isolates were susceptible to the combination of agents. Synergy was demonstrated in 26% of isolates. One uroseptic patient who had an organism resistant to both study agents, but susceptible to the combination, was cured. Two of six patients who did not receive vitamin K demonstrated abnormal coagulation patterns and one had an associated major bleeding complication. Although 12 of 64 (19%) patients who received vitamin K had at least one coagulation abnormality, there were no significant bleeding complications in this group.