"Our vision is to have a system that will automatically identify the blood culture isolate within 15 minutes of the culture being called positive," says Walsh. If a culture is positive at 2 AM, he says, automating this method could make it possible to identify the organism by 2:15 AM and send an electronic report to a patient's physician. They hope be begin testing and evaluating the feasibility of an automated form of the system in a clinical environment within months.
Rapid ID Procedure: An overall schematic of the simple three-step process (lyse-spin-read) is given in Figures 1a-c. Briefly, a 2.0 mL sample of warm (35-37oC) positive broth is removed from the test blood culture bottle and added to 1.0 mL of warm (35-37oC) selective lysis buffer (0.45% w/v Brij-O10 in 0.3M CAPS, pH 11.7), contained in a 15 mL screw capped polypropylene tube. The mixture was vortexed for 5 seconds at maximum speed and then placed in a 35-37oC waterbath for 60 seconds. After an additional 1-2 second vortex, 1.0 mL of the lysate was removed and layered onto a single 5/16 inch diameter polypropylene ball (CIC Ball Co.) floating on the surface of 0.5 mL of a solution of 24% w/v cesium chloride + 0.005% w/v Pluronic F-108 + 10 mM HEPES, pH 7.4 contained within an optical micro-centrifuge tube. The polypropylene ball was used to control the layering process and create an undisturbed interface. The tube was sealed with a screw-cap and centrifuged for 2 minutes at 10,000 rpm at 20-25oC in a microcentrifuge with A-8-11 swing-out rotor.
|Contact: Garth Hogan|
American Society for Microbiology