Association of aminoglycoside plasma levels with therapeutic outcome in gram-negative pneumonia

To determine the association of aminoglycoside plasma levels with therapeutic outcome in gram-negative pneumonia, the case reports of 37 patients from four prospective, randomized, controlled trials of gentamicin, tobramycin, and amikacin were analyzed. Twenty (54 percent) of these patients had a favorable outcome. Patients with maximal one-hour postinfusion (peak) levels of 7 μg/ml or greater for gentamicin and tobramycin or 28 μg/ml or greater for amikacin more often had successful outcomes (14 of 18, 78 percent) than those with levels less than this (six of 19, 32 percent) (p < 0.006). Patients with overall mean peak levels of 6 μg/ml or greater for gentamicin and tobramycin or 24 μg/ml or greater for amikacin more often had successful outcomes (14 of 20, 70 percent) than those with levels less than this (six of 17, 35 percent) (p < 0.04). The initial patient temperature, serum urea nitrogen/creatinine ratio, initial polymorphonuclear leukocyte count, and age were also associated with outcome; but by multivariate analysis, achieving an adequate peak concentration was the most important discriminating factor. These results suggest the potential importance of achieving adequate aminoglycoside levels in patients with gram-negative pneumonia.