ObjectiveTo understand serum trough concentrations (Cmin) of teicoplanin and target concentration achieved in severely infected patients after three days treatment with different loading doses of teicoplanin, and find out optimal loading dose. MethodsSeverely infected patients who admitted to the intensive care unit(ICU) of a hospital from February 1, 2016 to February 28, 2017 were enrolled in the study. According to different drug loading doses (teicoplanin standard dose: 6mg/kg; high dose:10mg/kg) and different creatinine clearance rates (Ccr: 50mL/min as standard value), patients were divided into four subgroups: group of standard dose and normal Ccr (GSD1), group of standard dose and low Ccr (GSD2), group of high dose and normal Ccr ( GHD1), group of high dose and low Ccr(GHD2). Serum Cmin, percentage of achieving target concentration, and adverse reactions of teicoplanin in different groups were compared. ResultsA total of 49 patients were enrolled in the study, 17 patients were in GSD group, Cmin on 4th day before administration was (5.98±2.67)mg/L; 32 patients were in GHD group, Cmin on 4th day before administration was (9.05±4.25)mg/L; Cmin in GHD group was higher than that in GSD group, and there was statistical difference between two groups（t=3.10，P=0.003）. Values of Cmin in GSD1, GSD2, GHD1, and GHD2 groups were (5.78±2.72), (6.34±2.78), (8.21±3.77), and (12.07±4.81 ) mg/L respectively, differences among four groups were statistically significant（F=4.766, P=0.006）. The Cmin in GHD2 group was higher than those in GHD1,GSD2, and GSD1 groups, percentage of achieving the target concentration were 9.09% (1/11), 16.67% (1/6), 28.00%(7/25), and 71.43% (5/7) respectively, differences were statistically significant（χ2=8.766, P=0.033）. Complications associated with teicoplanin such as rash, damage to hepatic and renal function were not observed in all patients during the treatment course. ConclusionWhether the Ccr is normal or not, target Cmin can not be achieved early in patients given teicoplanin with standard loading dose; in patients with low Ccr, given high loading dose, target Cmin can be achieved early; while in patients with normal Ccr, higher loading dose may be needed.