This patient should undergo chest radiography to exclude active tuberculosis infection. The patient is asymptomatic and is taking infliximab, a tumor necrosis factor α inhibitor, for management of her psoriasis. A tuberculin skin test (TST) reaction of 5-mm or larger induration is interpreted as positive in patients who are immunosuppressed, including those who are taking tumor necrosis factor α inhibitors or the equivalent of at least 15 mg/d of prednisone for 1 month or longer. Other patients for whom 5-mm or larger induration is considered positive include patients with HIV infection, organ transplants, and fibrotic changes on chest radiograph consistent with old tuberculosis, and recent contacts of a person with active tuberculosis. If the chest radiograph is negative, treatment for latent tuberculosis infection, usually consisting of daily isoniazid with pyridoxine (vitamin B₆) for 9 months, is recommended to decrease the risk for progression to active disease.

Testing with both the TST and interferon-γ release assay is not routinely recommended. According to the Centers for Disease Control and Prevention, using both tests may be helpful when the result of the initial test is positive and additional validation of infection is required before recommended treatment is initiated, such as in health care professionals who previously received the bacillus Calmette-Guérin vaccine or patients at low risk for infection and progression to active disease. Conversely, both tests may be helpful when the result of the initial test is negative and the risk for infection, active disease, and a poor outcome is increased, such as in patients infected with HIV or children younger than 5 years who have been exposed to a patient with active tuberculosis. Using both tests also may be helpful when the result of the initial test is negative but symptoms, signs, or imaging results are suspicious for TB and evidence of infection with M. tuberculosis is being sought. Because this patient does not fit into one of these categories, interferon-γ release assay would not be indicated.

Rifampin, isoniazid, pyrazinamide, and ethambutol would be recommended as initial therapy for a patient with active tuberculosis. This patient has no symptoms of active infection. Unless the chest radiograph suggests active tuberculosis, beginning four-drug antituberculous therapy is not indicated and would not be appropriate before further evaluation.

No additional intervention, including evaluation or therapy, would be inappropriate for this patient. Although she is asymptomatic, she is at risk for active tuberculosis if untreated for latent tuberculosis infection.