A student with an induration of 13 mm on a Mantoux test is asymptomatic. Which monotherapy is appropriate for this patient?

In the context of a Mantoux test, which is used to screen for tuberculosis (TB) infection, an induration of 13 mm is considered significant, particularly in individuals who are asymptomatic. This is indicative of latent tuberculosis infection (LTBI). The appropriate management for LTBI is the initiation of monotherapy with isoniazid.

Isoniazid is the first-line treatment for latent TB because it effectively reduces the risk of progression from latent to active TB disease. The standard duration for isoniazid therapy is typically six to nine months, depending on various factors, including patient health and risk factors.

The other choices listed, such as ethambutol, pyrazinamide, and streptomycin, are primarily used for the treatment of active tuberculosis disease rather than for latent infections. Ethambutol is typically utilized in combination therapy for active TB, pyrazinamide is also used in the treatment of active TB, and streptomycin is an older medication that is generally less favored in the current treatment protocols. Therefore, these medications are not appropriate for a patient with a positive Mantoux test who is asymptomatic and has latent TB.