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Once an MGIT tube is positive by fluorescence or visual observation, prepare a smear and stain with carbol fuchsin stain. 

Procedure:

In liquid medium, M.

The following observations can make tentative identification:

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.

The MGIT 960 offers a variety of reports which may be helpful in your daily workflow. Examples of these reports can be found in your binder.

Detection time can range from 24 hours to six weeks for MGIT. The pictorial representation of MGIT 960 culture detection is shown below:

• In automated systems, tubes are read continuously and flagged when positive.  Performing acid-fast bacteria (AFB) smear with Zeihl-Neelsen (ZN) staining determines the next steps.

Documentation of MGIT cultures is important to characterise if growth is positive for M. tuberculosis or unexpected result/contamination.

Usually, more than one specimen is collected from a patient. Therefore, it is not necessary to salvage a contaminated specimen if other specimens from the same patient are positive and not contaminated. However, if it is critical to have the results of a particular specimen that was contaminated, the broth may be reprocessed.

A high contamination rate indicates improper decontamination procedure. At the same time, too low contamination indicates over-treatment of the specimen that could also lower the culture positivity rate or increase the detection time. If in the MGIT it is more than 7-8%, then the decontamination procedure is not satisfactory and corrective measures should be taken: