Internal verification of BD BACTEC FX40 instrument for rapid detection of bloodstream infections

Abstract

Aim: The BD BACTEC FX40 automated instrument was evaluated for use by Ballarat Australian Clinical Laboratory (ACL) to aid in the detection of blood stream infections. Method: 20 organisms were chosen from the reference culture collection to be inoculated into two aerobic, two anaerobic and two paediatric blood culture bottles filled with designated volume of human blood. For each organism, 50 μL of the recommended dilution was aseptically added for each bottle with 5 mL of normal saline in each dilution tubes. There were 12 control bottles injected with sterile water. All bottles were loaded into the instrument. Bottles were removed as they flagged positive. A gram stain and culture were performed on each bottle that flagged positive. Identification by standard laboratory procedures was performed on all isolates. Result: All bottles that were expected to flag positive, flagged positive within the specified time frame listed. The time to detection for each bottle type with the organisms seeded into the blood culture bottles was recorded. Conclusion: All predicted positive blood culture bottles flagged positive except Streptococcus pneumonia in the anaerobic bottle. Controls remained negative. BACTEC FX40 instrument was fit for purpose given that it demonstrated acceptable agreement with inoculated organisms and culture.