Pulmonary tuberculosis (TB) is a serious infection caused by the bacterium Mycobacterium tuberculosis (MTB) that involves the lungs but may spread to other organs. TB is a contagious disease that can infect anyone exposed to MTB. While consumption (the former name for TB) is no longer a common cause of death in the United States, there are epidemics of multidrug-resistant tuberculosis in other countries and among some communities of homeless or disadvantaged people in the United States. There are also “atypical” mycobacteria that cause disease in immune-compromised individuals, including those with HIV/AIDS.
It is useful to distinguish primary and secondary TB infection.
  • Primary MTB infection is spread by air droplets from a cough or sneeze from a person infected with the bacterium and can affect anyone, but the clinical disease is limited except in people with weakened immune systems, as well as infants and the elderly. Most people recover from primary TB infection, but the infection stays inactive (latent, dormant) for years.
  • Secondary TB is the reactivation of a dormant infection with MTB, usually but not always in a person with a weakened immune system.

Several conditions that cause weakened immune systems can make people more susceptible to TB, including:
  • Diabetes 
  • Medicines to treat an autoimmune disease
  • Chemotherapy for cancer
  • HIV disease

Preventing TB
Tuberculosis is preventable. If you have been exposed to a person with an active TB infection, a PPD test (also called tuberculin skin test) can determine if you are infected.

If there is risk of exposure, you should have a test promptly with a follow-up test at a later date, if the first test is negative. A positive skin test does not mean that you have active disease or are contagious, only that you have come into contact with the TB bacteria. Many people test positive because they have been exposed to TB at some time, not necessarily recently.

Treatment of latent TB infection involves only one or two drugs for a few months, avoids development of active disease and makes longer treatment with more drugs unnecessary.

If you develop symptoms that could be related to TB at any time after you have a positive skin test, seek medical advice since prompt treatment will prevent you from spreading MTB to your family, friends and coworkers.

Symptoms of TB
Only some of the following symptoms of active pulmonary TB may occur during the primary infection (and they may be relatively mild in an otherwise healthy person) or a secondary reactivation of MTB infection:
  • Chest pain
  • Wheezing or difficulty breathing
  • Cough (usually with mucus, sometimes with blood)
  • Fever, sometimes with night sweats
  • Fatigue
  • Unintentional weight loss

Diagnosing TB
Patients with primary or secondary active TB have characteristic symptoms:
  • Lymph nodes in the neck or other areas may be swollen or tender
  • Lung sounds (crackles)
  • Chest fullness due to fluid around the lungs (pleural effusion)

The clinical diagnosis of TB is confirmed by one or both of the following tests:
  • Interferon-gamma release blood test
  • Sputum examination by microscope for acid-fast bacteria

The extent of disease is determined by imaging the lungs (and other parts of the body if there are symptoms that the TB has spread beyond the lungs) with a chest X-ray or computed tomography (CT) scan.

Treating TB
Treatment of active TB always involves a combination of several (usually four) medicines for six months or longer. Even for ordinary TB, effective regimens require many pills at several times of the day. If resistant TB is suspected, the drug regimens are more complex. Preventive therapy, on the other hand, may be only one or two pills a day for a shorter period.
When there is a concern that you may not take all the medicines exactly as directed, a health care provider may need to watch you take the prescribed medicines. This approach is called directly observed therapy (DOT). In this case, medicines may be given two or three times a week, as prescribed by a doctor.
To avoid spreading the disease to others, you may need to be isolated for the first two to four weeks of TB therapy until you are no longer contagious. Your doctor or nurse is required by law to report your TB to the local health department. Your doctor in consultation with the local public health authorities will determine whether you can stay at home with precautions to protect your family or need to be hospitalized for a time.


Our physicians at Houston Methodist specialize in treating tuberculosis at the following convenient locations.