How can one acquire primary cutaneous tuberculosis?

Primary-inoculation tuberculosis occurs from direct inoculation of M. tuberculosis into the skin and includes the chancre at the site and affected regional lymph nodes. The organism cannot penetrate intact skin and requires a break in the skin, such as a minor cut or abrasion. Reports have also implicated tattooing, ear piercing, circumcision, mouthto- mouth resuscitation, and needle-sticks. In some cases, there is no documented injury.

Semaan R, Traboulsi R, Kanj S: Primary mycobacterium tuberculosis complex cutaneous infection: report of two cases and literature review, Int J Infect Dis 12(5):472–477, 2008.