Reading MGIT 960 Tubes Manually

The beauty of the MGIT 960 tubes is that they can be read by the instrument and also manually. There are times AFB cultures are incubated at temperatures other than 37^oC. If that is the case, the MGIT tube can be incubated at an alternate temperature. These tubes would then need to be read manually with a Wood’s Lamp or other UV sources of the proper wavelength and intensity.

In the event of an instrument failure where the instrument is down for an extended period, you may decide to incubate the tubes offline. These tubes can also be read manually.

Manual readings should not be conducted in a darkened room or rooms with bright sunlight. Normal room lighting is appropriate. When using any UV source, one must always wear protective UV goggles.

To read the tubes manually, place the rack of tubes directly on top of the UV lamp. There is no need to take the tubes out of the rack. Some accounts leave a blank row between tubes. This can make it easier to see the fluorescence when reading the tubes.

Tilt the tubes/rack slightly so that the tubes are read at a slight angle. Look for fluorescence both at the sensor at the bottom of the tube and the meniscus at the top of the media line (the fluorescence of the sensor reflects in the meniscus). Place a positive and negative control at the end of the row to give visual assistance in the reading. Place the suspect between these two tubes to determine if the patient tube is positive. The fluorescence in the patient tube should be greater than the background fluorescence in the negative control but does not need to be as great as the fluorescence in the positive control to be considered positive.

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