Aminoglycoside treatment and mortality after bacteraemia in patients given appropriate empirical therapy: a Danish hospital-based cohort study

Abstract

The effectiveness and safety of aminoglycoside (AG)/beta-lactam combination therapy has been questioned in several meta-analyses. We examined the association between AG combination therapy and mortality and increase in serum creatinine in adult patients with bacteraemia given appropriate empirical antibiotic therapy. Historical cohort study based on prospective registration of bacteraemias in a Danish hospital 1996-2002. AG + beta-lactam was the recommended empirical therapy for severe sepsis. We identified 1,257 patients, of whom 969 received gentamicin or tobramycin (AG cohort); 288 patients not given AGs formed the non-AG cohort. We used Cox regression analysis to compare adjusted mortality rates; the association between AG therapy and increase in serum creatinine was analysed by logistic regression. The cumulative 30 day mortality in the AG cohort was 17.3% versus 18.1% in the non-AG cohort [adjusted mortality rate ratio (MRR) 1.02; 95% CI 0.74-1.39]. The adjusted 31-180 day MRR in the AG cohort was 1.72 (95% CI 1.15-2.55). AG therapy was associated with lower 30 day mortality in patients with an abdominal focus (adjusted 30 day MRR 0.52; 95% CI 0.24-1.10) or a urinary tract focus (adjusted 30 day MRR 0.48; 95% CI 0.22-1.08), but with a worse prognosis in patients with a respiratory tract focus (adjusted 30 day MRR 2.06; 95% CI 0.93-4.53). An increase in serum creatinine of >or=45 micromol/L was observed similarly often in AG- and non-AG-treated patients [14.1% versus 12.4%, adjusted odds ratio 1.06; 95% CI 0.63-1.79]. Among patients with bacteraemia receiving appropriate empirical coverage, AG combination therapy was not associated with increased 30 day mortality and only a modest risk of raised serum creatinine. The longer-term prognosis should, however, be explored further.