Effect of aminoglycoside and β-lactam combination therapy versus β-lactam monotherapy on the emergence of antimicrobial resistance:: A meta-analysis of randomized, controlled trials

Background. The addition of an aminoglycoside to a Beta-lactam therapy regimen has been suggested to have a beneficial effect in delaying or preventing the development of antimicrobial resistance. We studied the effect of aminoglycoside/beta-lactam combination therapy versus beta-lactam monotherapy on the emergence of resistance. Methods. We performed a meta-analysis of randomized, controlled trials (RCTs) that compared aminoglycoside/beta-lactam combination therapy with beta-lactam monotherapy and that reported data regarding the emergence of resistance (primary outcome) and/or development of superinfection, treatment failure, treatment failure attributable to emergence of resistance, treatment failure attributable to superinfection, all-cause mortality during treatment, and mortality due to infection. Data for this meta-analysis were identified from the PubMed database, Current Contents database, Cochrane central register of controlled trials, and references in relevant articles. Results. A total of 8 RCTs were included in the analysis. beta-Lactam monotherapy was not associated with a greater emergence of resistance than was the aminoglycoside/b-lactam combination (odds ratio [OR], 0.90; 95% confidence interval [CI], 0.56 - 1.47). Actually, beta-lactam monotherapy was associated with fewer superinfections (OR, 0.62; 95% CI, 0.42 - 0.93) and fewer treatment failures (OR, 0.62; 95% CI, 0.38 - 1.01). Rates of treatment failure attributable to emergence of resistance (OR, 3.09; 95% CI, 0.75 - 12.82), treatment failure attributable to superinfection (OR, 0.60; 95% CI, 0.33 - 1.10), all-cause mortality during treatment (OR, 0.70; 95% CI, 0.40 - 1.25), and mortality due to infection (OR, 0.74; 95% CI, 0.46 - 1.21) did not differ significantly between the 2 regimens. Conclusions. Compared with b-lactam monotherapy, the aminoglycoside/beta-lactam combination was not associated with a beneficial effect on the development of antimicrobial resistance among initially antimicrobial-susceptible isolates.