Final answer:
The most important test to confirm a tuberculosis infection after exposure to Mycobacterium tuberculosis is the PPD intradermal test.
Step-by-step explanation:
The most important test to confirm the presence or absence of a tuberculosis infection after exposure to Mycobacterium tuberculosis is the PPD intradermal test, also known as the tuberculin skin test. This test involves injecting tuberculin protein derivative into the skin and checking for a raised wheal or induration after 48-72 hours. A positive result indicates exposure to the bacteria and an immune response.