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Quality Control of DST is critical to ensure the test is functioning properly so that reliable results can be interpreted. ​

Steps in Quality Control in DST result interpretation include: 

1. SIRE/ Second- line and PZA QC

• Carefully entering the tubes into MGIT 960​
• Carefully scanning the DST set carrier into the BACTEC MGIT 960 instrument.

2. Interpretation of results
 

Quality control of MGIT DST inoculum is essential for quality DST results. The different aspects of inoculum preparation include:

1. Using the right inoculum​​
2. Using pure cultures only​
3. Using fresh cultures​
4. Using slant < 14 days

Quality controls procedures are essential to generate quality DST results. Quality procedures are essential when using QC strains and reagents and preparing and using drugs for DST. These include:

The definite diagnosis of tuberculosis demands that M. tuberculosis be recovered on culture media and identified using differential in vitro tests. Hence using laboratory standards is an important aspect of ensuring quality processes in all aspects of MGIT DST. 

These include the following:

1. Standard laboratory biosafety measures as applicable to TB containment laboratories for handling culture isolated and performing DST

2. Trained staff to use standard operating procedures for equipment and laboratory methods 

MGIT DST Quality Control

Quality control of MGIT DST is critical to laboratory testing, as it ensures the accuracy and consistency of the test processes and the results reported. 

Frequency: 

It is important to perform quality control (QC) of drug susceptibility testing periodically. This testing must be performed:

• For each new batch of reagents (MGIT drug kits, other drugs, media, etc.) 

Retesting MGIT DST Results

The cause for the unexpected/false profile of DST isolate can be due to various reasons that reflect quality aspects of the laboratory as well as the characteristic of the MGIT growth. The following need to be looked into as cause for unexpected/false profiles of DST isolate:

1. Laboratory procedures:

Troubleshooting False Resistant DST Results

The common reasons for getting false resistant DST results, along with their corrective actions, are given in the table below:

Troubleshooting False Susceptible DST Results

The common reasons for getting false susceptible DST results, along with their corrective actions, are given in the table below:

Troubleshooting Non-interpretable DST