Efficacy of amdinocillin and lack of nephrotoxicity when combined with a second beta-lactam antibiotic for therapy of serious gram-negative bacillary infections.

Seventy-eight patients with serious gram-negative bacillary infections were assigned at random to receive either amdinocillin or an aminoglycoside. In addition, each patient was also given a broad-spectrum penicillin or cephalosporin antibiotic. The clinical response to treatment was comparable in the two groups. Cures were effected in 35 (92 percent) of 38 patients treated with amdinocillin and a beta-lactam antibiotic, compared with 37 (93 percent) of 40 patients who were treated with an aminoglycoside/beta-lactam combination. For the entire group, only five (7 percent) of the 75 infecting organisms were resistant in vitro to the treatment beta-lactam or amdinocillin combination, and similarly only two (3 percent) organisms were resistant to the treatment aminoglycoside (p = 0.44). Although drug-related toxicity occurred with equal frequency in the two groups, six patients treated with an aminoglycoside experienced nephrotoxicity compared with none of the patients who received amdinocillin (p = 0.034). Thus, amdinocillin plus a broad-spectrum beta-lactam antibiotic may provide suitable empiric therapy for many patients with presumed gram-negative infection and so avoid the risk of aminoglycoside-induced nephrotoxicity.