Methods for inactivation and extraction of acid-fast bacteria from liquid media for characterization and/or identification using mass spectrometry

A method for inactivation and extraction of acid-fast bacteria in a test sample, the method comprising the following sequential steps:

• (a) transferring a 3 mL test sample from a positive liquid culture containing acid-fast bacteria to a first tube within 24-72 hours a post-positive result, wherein the first tube comprises a body having a volume of 5 mL, a first end to the body having an opening, and a second end to the body having a frustoconical portion ending in a concave tip;
• (b) centrifuging the first tube to pellet the acid-fast bacteria in the concave tip and subsequently decanting a first supernatant, wherein the frustoconical portion ending in the concave tip is configured to retain the pellet of acid-fast bacteria in the concave tip while decanting at least 90% of the first supernatant;
• (c) blotting the first tube to remove excess liquid;
• (d) resuspending the acid-fast bacteria pellet in alcohol to generate a first suspension;
• (e) transferring the suspension from the first tube to a second tube containing beads to form a second suspension;
• (f) agitating the second tube to break up clumps and disrupt acid-fast bacteria cells in the second suspension;
• (g) incubating the second suspension for at least about 5 minutes to inactivate the acid-fast bacteria in the test sample to form an inactivated second suspension.