Comparison of yield of microorganisms in cord blood between two automated blood culture systems / 中国输血杂志

ABSTRACT

【Objective】 To compare the difference in the detection rate of microorganisms in cord blood between BACTEC FX and BacT/ALERT 3D automated blood culture systems, and to compare the influence of incubation time and different types of culture sample on the detection rate of microorganisms in cord blood. 【Methods】 Cord blood samples prepared from April to August 2020 in Sichuan Cord Blood Bank(n=4 358) were selected, and 20 mL of plasma was used as culture samples for microbial detection. In addition, cord blood samples prepared in the same months of 2021(n=4 057) were selected, and 19 mL of plasma plus 1 mL of final product was used as culture samples for microbial detection. The total sample size was 8 415, of which 4 849 samples(2 458 in plasma group and 2 391 in plasma plus final product group) were assigned to the BACTEC FX system, and 3 566 samples(1 900 in the plasma group and 1 666 in the plasma plus final product group) to the BacT/ALERT 3D system. All samples were cultured for 7 days, and culture data were recorded on day 5 and day 7. Positive results were confirmed by Gram staining. 【Results】 The positive rate detected by the BACTEC FX system was higher than that of the BacT/ALERT 3D system(4.08% vs 2.69%), with statistically significant difference(P0.05) detected by the BacT/ALERT 3D system. With quality control strains, there were significant differences in TTP between these two systems for Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Clostridium sporogenes, and Bacillus subtilis(P0.05). 【Conclusion】 This study suggests that the selection of BACTEC FX blood culture system with incubation time of not less than 7 days and plasma plus final product as culture samples may improve the detection rate of microorganisms in cord blood.