Tuberculosis (TB) Treatment and Vaccine

A person with a positive skin test, normal chest X-ray, and no symptoms likely has few TB germs in an inactive state and is not contagious. Treatment with an antibiotic may still be recommended to prevent TB from becoming active. The antibiotic used for this is isoniazid (INH). Taking INH for six to 12 months will prevent TB from becoming active in the future. However, INH may not be suitable for pregnant individuals or those with alcoholism or liver disease, as it can have side effects. Side effects can include a rash, tiredness, or irritability. Liver damage from INH is rare but can be fatal, especially in older individuals (known as INH hepatitis). During INH therapy, a doctor should monitor the patient’s liver using blood tests called "liver function tests." Another side effect of INH is a decreased sensation in the extremities, which can be prevented by taking vitamin B6 (pyridoxine) along with INH. A person with a positive skin test, abnormal chest X-ray, and TB bacteria in their sputum has active TB and is contagious. Active TB is treated with a combination of medications, including INH. Rifampin, ethambutol, and pyrazinamide are commonly used in conjunction with INH to treat active TB. Initially, four drugs are taken to kill potentially resistant strains, which is then reduced to two based on drug-sensitivity testing. Treatment typically lasts for months or even years. The success of TB treatment relies on patient compliance. Some locations demand direct monitoring of patient compliance, where medication is given one dose at a time and patients must swallow it in the presence of health department staff. Researchers are investigating new agents like nitroimidazo-oxazine, sutezolid, and delamanid for TB treatment. Surgery may also be considered in cases where medication fails, but surgery is now uncommon. Without treatment, tuberculosis can be fatal, so early diagnosis is crucial. Individuals exposed to TB should be examined by a doctor for signs and screened with a TB skin test.

What is drug-resistant TB?

Drug-resistant TB has become a significant issue due to poorly managed TB care and is seen most commonly in certain populations. INH-resistant TB is particularly prevalent in Southeast Asia, possibly due to INH-like substances in cough syrups. Drug resistance can result from poor patient compliance, inadequate or inappropriate dosing or prescribing of medication, poorly formulated medications, or inadequate supply. Multidrug-resistant tuberculosis (MDR TB) refers to organisms resistant to at least two first-line drugs. Extremely drug-resistant tuberculosis (XDR TB) is resistant to three or more second-line treatment drugs and is frequently found in former Soviet Union and Asian countries. Preventing the spread of XDR TB is crucial. WHO recommends improving basic TB care, developing proper laboratories for detecting resistant cases, and prompt treatment when drug-resistant cases are found. Collaboration between HIV and TB care is also important for limiting the spread of tuberculosis. Improved drug susceptibility testing can optimize treatment strategies. The development of highly-resistant organisms remains a concern.

Is there a vaccine against tuberculosis?

Bacille Calmette Guérin (BCG) is a vaccine given in many parts of the world for protection against active tuberculosis, particularly in infants and children. However, it is not routinely administered in the United States. BCG vaccination can cause confusion when diagnosing TB as future tests may remain positive. Furthermore, TB can still occur in adults who have had the BCG vaccine, questioning its real effectiveness. A new blood test called QuantiFERON-TB Gold can help differentiate between a prior BCG vaccine and a positive test due to TB infection. This test measures the immune response in the patient’s blood after mixing it with substances that produce a TB-like immune response. It is not perfect, but when used alongside clinical information, it helps distinguish a real TB infection from a positive reaction due to a prior BCG vaccine.

What’s in the future for TB?

TB could have been eliminated by now through effective treatment, vaccinations, and public-health measures, but the emergence of HIV changed the situation. HIV caused a significant increase in TB incidence due to the suppression of the immune system. The HIV epidemic in Africa raises concerns about the development of MDR TB and XDR TB in this population. Controlling HIV and TB together is key to preventing the spread of both sensitive and resistant strains. Better drug susceptibility testing and more effective therapy from the onset of treatment can hopefully reduce the prevalence of resistant organisms.

Medically reviewed by Robert Cox, MD; American Board of Internal Medicine with subspecialty in Infectious Disease

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