Under Development

Error or indeterminate DST results are reported when certain conditions occur that may affect the test. These results are designated by the alphabet ‘X’ followed by a code. Following two types of such errors are encountered:

MGIT 960 DST Inoculum Troubleshooting

MGIT 960 DST Equipment and Reagents Troubleshooting

If the BACTEC™ MGIT™ instrument malfunctions or operates unusually in any way, an error message will appear on the instrument. These messages are in numerical order, along with possible causes of the message and corrective actions are listed below.

Table: Errors encountered during the operation of the BACTEC™ MGIT™ instrument and their corrective actions

Final Result Reporting

Once the DST results are validated and finalized, these need to be communicated to the requesters. NTEP guidelines mandate the reporting of DST results to the requesting district/physician through Ni-kshay within the stipulated turn-around time. The following steps are involved in reporting the DST results in Ni-kshay:

MGIT DST testing logs are maintained by the laboratory for QC purposes to record information on the Lot number of MGIT tubes and drugs used along with their expiry dates. A sample DST log is shown here that laboratories can adapt and use as per their requirements:

LC DST Recording and Reporting

LC DST Recording

Validation of Resistant/Unexpected MGIT DST Results

1. Validation of Resistant MGIT DST Results

Unloaded MGIT DST Report

A completed DST in the Bactec MGIT-960  instrument is indicated by a red “+” on the drawer. The following steps are involved in removing the completed DSTs from the instrument and printing the “Unload AST Set” report:

Procedure for Reading MGIT DST Results

Principle of MGIT DST Reading:

Two Mycobacterial Growth Indicator Tubes (MGITs)  are inoculated with the test culture. Then, a known concentration of a test drug is added to one of the MGIT tubes (drug-containing tube), and growth is compared with the MGIT tube without the drug (growth control).