Abstract: Objective To evaluate the effects of application of vancomycin in the early stage of patients with extremely severe burn, in order to provide reference to drug for anti-infection treatment in the early stage of patients with extremely severe burn. Methods Data of 15 patients of Kunshan explosion on August 2nd, 2014, admitted to the Department of Intensive Care in our hospital were retrospectively analyzed. The clinical efficacy of continuously intravenous dripping of vancomycin (combined with imipenem) in the early stage of burns (before and on post burn day 14) was analyzed. (1) The steady state plasma concentration of vancomycin was monitored respectively 30 min before the third, sixth, and tenth medication with direct chemiluminescent imaging method. (2) The distribution of Gram-positive bacteria of patients during hospitalization and their drug resistance to 14 antibiotics commonly used in clinic were analyzed. (3) Serum level of procalcitonin (PCT), white blood cell count, percentage of neutrophils before and after treatment, and efficacy grade of anti-infection treatment in the early stage of burns were analyzed. (4) Serum levels of aspartate transaminase (AST), alanine aminotransferase (ALT), creatinine before and after treatment, and the adverse effects during medication were analyzed. The WHONET 5.5 statistical software was used to analyze the distribution of Gram-positive bacteria in all the pathogens, and the status of drug resistance of Gram-positive bacteria to 14 antibiotics. Data were processed with Wilcoxon rank sum test. Results (1) Twenty-nine times of steady state plasma concentration monitoring were performed in the patients in total, with the steady state plasma concentration of vancomycin from 4.3 to 42.1 μg/mL. In the monitoring before third, sixth, and tenth medication, the percentages of result reaching the standard were respectively 1, 3/14, and 2/7. (2) A total of 79 Gram-positive bacteria were isolated, including 49 (62.03%) strains of Staphylococcus aureus, 9 (11.39%) strains of Staphylococcus haemolyticus, 7 (8.86%) strains of Staphylococcus epidermidis, 12 (15.19%) strains of Enterococcus faecium, and 2 (2.53%) strains of Enterococcus faecalis. The above-mentioned Staphylococcus strains were with high drug resistance to antibiotics including penicillins, erythromycin, ciprofloxacin, and low drug resistance to linezolid, teicoplanin, and nitrofurantoin. The above-mentioned Enterococcus strains were with high drug resistance to antibiotics including erythromycin, ciprofloxacin, gentamicin, and low drug resistance to linezolid and teicoplanin. The above-mentioned Staphylococcus strains were all sensitive to vancomycin. Two strains of vancomycin-resistant Enterococcus were detected in the above-mentioned Enterococcus strains. (3) Serum level of PCT, white blood cell count, percentage of neutrophils of patients were (8.1±7.5) ng/mL, (24±10)×10⁹/L, and 0.898±0.029 before treatment, which were significantly higher than (3.0±2.8) ng/mL, (12±5)×10⁹/L, and 0.867±0.016 after treatment (with Z values respectively -2.103, -3.237, and -3.068, P<0.05 or P<0.01). After the early treatment, excellence, progess, and invalid results were achieved in 7, 5, and 3 patients, with the effective percentage of 4/5 in clinic. (4) There were no statistically significant differences in serum levels of AST, ALT, and creatinine of patients between before and after treatment (with Z values respectively-0.057, -1.508, and -1.363, P values above 0.05). Only one patient had liver and renal dysfunction during treatment. Conclusions The positive and reasonable use of vancomycin can remove most of the Gram-positive bacteria, and control the development of sepsis combined with imipenem in the early stage of patients with extremely severe burn. However, the dose of vancomycin should be individualized and the steady state plasma concentration should be monitored to maintain the blood concentration within the safe and effective range, so as to improve the rational use of vancomycin.