Rifampin and isoniazid are primarily used to treat which of the following conditions?

Rifampin and isoniazid are antibiotics that play a crucial role in the treatment of tuberculosis, a bacterial infection primarily affecting the lungs but can also impact other parts of the body. Their effectiveness comes from targeting the unique aspects of Mycobacterium tuberculosis, the bacterium responsible for tuberculosis.

Rifampin works by inhibiting bacterial RNA synthesis, which is critical for bacterial growth and reproduction, while isoniazid interferes with the synthesis of mycolic acid in the bacterial cell wall. This dual approach helps to eradicate the infection more effectively and prevent the development of drug resistance. The combination of these two drugs is the cornerstone of tuberculosis therapy and is used in both active and latent forms of the disease.

On the other hand, conditions like psoriasis, depression, and sinusitis do not involve the specific bacterial strain that these antibiotics target. Psoriasis is a chronic skin condition, depression is a mental health disorder, and sinusitis typically results from viral infections, all of which are treated with different classes of medications that are suited to their specific underlying causes. Thus, the indication of rifampin and isoniazid aligns strictly with tuberculosis treatment.