BD BACTEC Blood culture system: Introduction, principle and processing

BD BACTEC Blood culture system: Introduction, Principle and Processing

BD BACTEC Blood Culture System

Introduction BD BACTEC Blood Culture System

Conventional blood culture Vs BD Bactec

Blood culture is used to detect blood-borne pathogens essential in identifying bacteria responsible for bacteremia and sepsis. Nowadays, Several automated blood culture systems are available commercially. The advantages of all those such systems are the elimination of the need for blind subculture and the shortening of the usual incubation period of five to seven days. It also minimizes contamination and bio-hazard risk. It is very important for the hospitals to choose a reliable system that can not only give them the best outcome in terms of turnaround time to improve patient outcomes by decreasing morbidity and mortality but also lower patient costs.

Some models of BD BACTEC and its features

BD BACTEC™ FX Instruments

Impacting Patient Care

The BACTEC™ FX blood culturing instruments used with patented resin-containing media have shown higher rates of organism recovery, allowing for proper diagnosis and treatment of bloodstream infections.

The BD BACTEC™ FX builds on the proven superior fluorescence detection technology, exceptional media performance, and instrument reliability of the BD BACTEC™ 9000 blood culture systems.

The BD BACTEC™ FX system is designed for performance, efficiency, ease of use, and flexibility – keeping pace with the rapidly changing needs of the laboratory. The system can streamline workflow and minimize process steps – two factors that are key to reducing labor costs.

The most common configuration of the FX is a two-module system designed as a stack. The stack contains two drawers, each with a 100-vial capacity.

Conventional media vs Resin media

Our patented BD BACTEC resin media have been shown to effectively neutralize a wide variety of antibiotics, allowing the growth of microorganisms that may not occur with conventional media. This greater recovery leads to more accurate diagnosis and effective treatment, which can, in turn, lead to shorter hospital stays, lower patient costs, and greater overall laboratory and institutional efficiency.

Principle of BD BACTEC

When microorganisms are present in culture vials, they metabolize nutrients in the culture medium, releasing carbon dioxide into the medium. A dye in the sensor at the bottom of the vial reacts with CO2. This modulates the amount of light that is absorbed by a fluorescent material in the sensor. A photodetector at each station measures the level of fluorescence, which corresponds to the amount of CO2 released by organisms. Then the measurement is interpreted by the system according to pre-programmed positivity parameters. At system startup, the onboard computer performs self-diagnostics and downloads operating instructions to the drawer rows. Then the instrument(s) automatically begin testing. Light Emitting Diodes (LEDs) behind the vials illuminate the rows, activating the vials’ fluorescent sensors. After a warm-up period, the instrument’s photodetectors then take the readings. A test cycle of all rows is completed every ten minutes. Positive cultures are immediately flagged by an indicator light on the front of the instrument, an audible alarm, and are displayed on the LCD display. When positive vials are identified, the lab technologist pulls them from the instrument for confirmation of results, and for isolation and identification of the organism.

Processing New Blood Cultures

Method

Select a drawer that has available stations, and open that drawer
The barcode scanner turns on
Scan a vial sequence barcode label
The Vial Entry display appears and the Sequence, Media, and default Protocol are automatically entered
If you did not scan the Accession, scan or enter it now
To change the protocol tap the “modify” button, then tap the up arrow to increase or down arrow to decrease the protocol length
Place the vial into an available station (solid green indicator)
When a vial is placed into the last available station in a drawer, the Activity Complete tone sounds (3 beeps).
To continue entering vials, select another drawer with available stations

Positive and Negative Vials

Notification of positive and negative vials

The system notifies you of new positive cultures in several ways:

Positive Vial audible alarm sounds
Station Indicators: FLASHING RED or FLASHING AMBER / RED (alternating) -Anonymous Positive
A message box appears on the screen
Positive vial system indicator for that drawer illuminates
On the Status display, the “positives” icon is active (the color is red, not grayed out) and the number of positive vials in the drawer is shown

Out-of-Protocol Negatives are indicated by the following:

Negative vial system indicator for that drawer illuminates
On the Status display, the “negatives” icon is active and the number of negative vials in the drawer is shown Station indicators: FLASHING GREEN

Removing positive vials

Select a drawer that has positive stations and open the drawer by pulling it out. The barcode scanner turns on. All positive, final negative, available, and anonymous (all variations) are indicated by the appropriate lit or flashing station indicators. Tap the “remove positives” button on the Status display, OR Remove a vial from a FLASHING RED (positive) or FLASHING AMBER / FLASHING RED (anonymous-positive) station. The Positive Removal display appears. (If an anonymous positive vial was removed, the ID Anonymous display appears. Scan the sequence and accession for the anonymous positive vial and tap the “Save” button. Then tap the “Exit” button to return to the Positive Removal display.) If the Show Related Vials function is enabled in the configuration, the LEDs of vials with the same accession number illuminate GREEN (in the current drawer), and the Culture – Specimen display shows the related vials in the Vial Window (not applicable to Positive / Anonymous vials).

Remove any related vials if desired, and either confirm or scan the sequence number (depending on the system prompt). When you have finished removing related vials, tap the “exit” key to return to the Positive Removal display

Removing negative vials

Select a drawer that has negative stations and open the drawer by pulling it out. The barcode scanner turns on. All positive, final negative, and anonymous (all variations) are indicated by the appropriate flashing station indicators. For Single Vial Removal- Tap the “remove negatives” button on the Status display, OR Remove a vial from a FLASHING GREEN (negative) station and scan it.

The Negative Removal display appears. Remove and scan all the negative vials. (If any vial sequence numbers were entered manually, the system asks you to verify that the sequence number is correct. You must manually confirm that the sequence number on the vial is the same as the one shown on the screen, and tap the “Verified” button.)

For Batch Vial Removal

Remove the negative vials from the FLASHING GREEN station. These vials do not have to be scanned (and the scanner does not turn on). Any vials left in the instrument remain in the database as negatives. Counters on the display are updated dynamically as vials are removed. When all negatives are removed from the drawer, the “activity complete” tone sounds.

Processing Positive Vials

Remove the vial from the instrument and place it in a biological safety cabinet.
Invert the vial to mix the contents.
follow “Universal Safety Precautions” to vent each presumptive positive blood culture vial. Use a venting needle.
Remove aliquot from the vial for stain preparations (Gram and/or AFB).
Subculture vials according to the Gram stain and/or AFB stain results.
Report preliminary results only after stain preparation.
Perform identification and susceptibility of the organism(s) grown on solid media according to your laboratory protocol.

universe84a