Abstract:

Objective To evaluate the influence factors that might affect the results of blood culture in Shanghai Jiaotong University School of Medicine Ruijin Hospital. Methods Blood specimens were cultured by BD BACTECFX automatic blood culture instrument,and the microorganisms were identified by VITEK MS detection system. The effects of the variables on the results of blood culture were evaluated by Logistic regression analysis and receiver operating characteristic（ROC）curve. Results A total of 1 852 blood culture bottles were collected,155 bottles were positive,and the positive rate was 8.37%. Gram positive bacteria accounted for 38.06%（59 isolates）,Gram negative bacteria accounted for 58.06%（90 isolates）,and fungi accounted for 3.87%（6 isolates）. The average time of reporting positivity was 34.81 h. Logistic regression analysis showed that age [odds ratio（OR）=1.161,95% confidence interval（CI） 1.069-1.260,P=0.000],the temperature of the patients on the time of blood specimen collection（OR=2.680,95%CI 1.918-3.744,P=0.000）,the volume of blood collection（OR=1.475,95%CI 1.059-2.055,P=0.022）and white blood cell count（OR=3.758,95%CI 2.676-5.278,P=0.000）were influence factors for the positive rate of blood culture. Conclusions Age,the volume of blood collection,white blood cell count and the temperature of the patients on the time of blood specimen collection are correlated to the positive rate of blood culture. Collecting blood specimens correctly may increase the detection rate of blood stream infection（BSI）,which is helpful to clinical anti-infection treatment.

Key words: Blood culture, Blood stream infection, Blood specimen, Influence factor