SIP

Subject Title: CCHEM/ HAEM/ LMQA/ MMIC
Topic : Bacteriology - Blood Culture

Definition:
A blood culture is a test to determine if microorganisms such as bacteria, mycobacteria, or fungus are present in the blood. A sample of blood is put in a special laboratory preparation and is incubated in a controlled environment for 1 to 7 days.

Principle:
Bacteria growing in a suitable broth causes turbidity of medium or gas production. The BACTEC Fluorescent series blood culture system, detects carbon dioxide (CO2) production by multiplying bacteria.

Materials:
Media contains Soybean-Casein Digest broth with resin and 0.05% w/v sodium polyanethol sulfonate (SPS). All bactec media are dispensed with added CO2. Anaerobic media are prereduced and dispensed with CO2 and N2.

Procedures:
1. Vials are arranged and labeled in racks.
2. If requisition form presents infectious endocarditis in its clinical diagnosis, a red ribbon is tied on the vials for indication.
3. Vials’ barcodes are scanned and incubated aerobically at 35ºC and are agitated throughout the routine 5-day protocol.
4. Negative vials are removed after few days while positive vials are removed from BACTEC machine for flagging, Gram Stain and subculture in appropriate plates.

False Negative Results:
Delay in transportation could lead to false negative results. Inoculated Bactec/F Plus vials can only be left at room temperature up to 48 hours before placing into BACTEC machine.

For photos on BACTEC system and procedures after flagging positive vials, please visit here. (Azhar's entry - linked with permission)


Boon Ching
TG01