Incubation and Storage of Culture Isolates

The MGIT system automatically and continuously incubates and monitors tubes once they are placed in a station; there is no need to remove the tubes from the instrument. 

Cultures during incubation:

1. Cultures remain in their stations until signalled “positive”, or if no growth is detected after 42 days incubation, are signalled “negative”. 

2. If an instrument-positive tube is determined to be smear-negative for either mycobacteria or contaminants, the tube may be re-entered into the instrument, but within 5 hours of removal.

3. If the tube is not returned within the 5-hour re-entry window, the associated data is removed from the instrument’s database, and the tube will be monitored as a newly entered tube.

The MGIT instrument will record the date each tube was entered.
• Do not turn tubes after placing them in the station.
• Do not remove tubes unless they are positive or out-of-protocol negatives (negative at 42 days).
• Do not reassign tubes to a new station.

Resource

Mycobacteriology Laboratory Manual

Assessment