Tuberculosis (TB) is a bacterial infection caused by Mycobacterium tuberculosis. Typically, the bacteria attacks the lungs. However, it can also infect other parts of the body including the brain, spine, abdomen, kidneys, heart, and skin. Symptoms include fever, cough, weight loss, and weakness. In some cases, people with TB infections may not have any symptoms at all. A person is infected with TB when they are exposed to the bacteria through inhalation or ingestion. The bacteria then grow inside macrophages, cells that fight off infection and cause them to produce substances that damage surrounding tissue. This in turn leads to inflammation of the lung tissue which can be seen on imaging studies as thickened areas of the lung called tubercles. If left untreated, this disease can spread throughout the body causing various organs to fail. Currently, there are two main treatments for TB: first-line drugs and second-line drugs. Drugs used to treat TB are called anti-tubercular drugs (ATDs). First-line ATDs include isoniazid, rifampin, pyrazinamide, and ethambutol. These drugs work best if taken together every day.