False-negative results obtained with the Gen-Probe Amplified Mycobacterium tuberculosis direct test caused by unrecognized inhibition of the amplification reaction.

The Gen-Probe Amplified Mycobacterium tuberculosis direct test is widely used in the diagnosis of tuberculosis. Specimens may contain amplification inhibitors, potentially leading to false-negative results if unrecognized. We report a failure to detect inhibition, despite adherence to the inhibition testing guidelines provided on the label, and recommend changes.