Effect of Delayed Entry into 2 Different Blood Culture Systems(BacT/Alert 3D and BACTEC 9120) on Culture Positivity / 中华医院感染学杂志

ABSTRACT

OBJECTIVE To evaluate the effect of delayed entry(0-24 h) into BacT/Alert 3D and BACTEC 9120 and the effect of 2 incubation temperatures(22 ℃ vs 35 ℃) on culture positivity.METHODS We utilized the BacT/Alert system with FA bottles and the BACTEC 9120 system with Plus(Aerobic) bottles.Four clinical bacterial species,Staphylococcus aureus,Escherichia coli,Streptococus pneumoniae,Candida albicans,were used as the test strains.and 5 ml of blood were added to each bottle.Each species was inoculated into the bottles 3 times at an inoculum size of 10 CFU/ml,102 CFU/ml and 108 CFU/ml,respectively.The inoculated bottles were cultured using the respective instruments after they were allowed to stand at room temperature(22 ℃)and 35 ℃ for 0,8,16 and 24 h.Time-to-detection and culture positivity were evaluated.RESULTS The delay in transportation of blood culture bottles stored at room temperature(22 ℃) or 35 ℃ had no effect on the recovery rate for BACTEC 3D at less than 24 h preincubation time and for BacT/Alert 9120 at less than 16h preincubation time.The positivity rate decreased significantly for BacT/Alert 9120 for 24 h of delay.Culture positivity of BacT/Alert 3D was higher than BACTEC 9120 for 24 h of delay.CONCLUSIONS The delayed entry for BacT/Alert 3D should be within 24 h,but the delayed entry for BACTEC 9120 should be within 16 h.