US Pharm. 2018;4:13-14.
Potentially Fatal Bacterial Infection
Tuberculosis (TB) is a bacterial infection of the lungs that can spread to other parts of the body, including the brain, spinal cord, and kidneys. The infection is spread from person to person through the air in droplets of mucus released when one coughs, sneezes, or even talks. Although it is less prevalent in the United States, more than 10 million people worldwide have active TB. With long-term antibiotic treatment, TB is curable, but drug-resistant strains can occur when antibiotics are taken incorrectly or stopped too soon. When left untreated, TB can be fatal, especially in high-risk populations.
Latent TB Is Widespread
As many as 2.5 billion people across the globe are infected with TB, but not all of them develop active disease. In most people, when the organism that causes TB (Mycobacterium tuberculosis) enters the lungs, the immune system responds by forming a granuloma, which is a collection of immune cells that create a barrier around the bacteria. TB that is surrounded by a granuloma is known as latent TB. Latent TB does not cause symptoms, is not contagious, and can often go unrecognized for an entire lifetime.
Active infection occurs in 5% to 10% of people exposed to M tuberculosis. People at the highest risk for active TB disease are those with compromised immune systems from HIV, diabetes, organ transplants, substance abuse, chemotherapy, or steroids that reduce immune function. People with active TB infection are symptomatic and can spread M tuberculosis to others.
Symptoms and Diagnostic Tests
The symptoms of TB depend on the area of the body that is affected. The most common site of infection is in the lungs. TB causes symptoms such as a cough that lasts more than 3 weeks, pain in the chest, blood in the phlegm, night sweats, no appetite and weight loss, fatigue, fever, and chills. TB infection in the bones can present as aches and pains in the joints. Physicians rely on the nature of the symptoms and a comprehensive medical history, including travel history, when diagnosing a patient with TB. The tuberculin skin test, or Mantoux test, is also given to confirm the presence of TB. Patients with both active and inactive TB can have a positive skin test, so a positive test result requires further evaluation to determine whether an active infection is present.
Antibiotic Treatment Can Last Many Months
Today, the prognosis for a person infected with TB is good because there are effective medications for treating and curing the disease. Antibiotic treatment for TB continues much longer than that for other common infections, with individual treatment lasting 6 to 9 months, on average. More recently, clinical trials have demonstrated that 4 months of treatment with a combination of medications may effectively prevent latent TB from becoming active. The most potent or first-line drugs include isoniazid, rifampin, ethambutol, and pyrazinamide. After 2 to 3 weeks of active treatment, TB is no longer contagious. Although a TB vaccine exists—bacillus Calmette-Guérin—its use is not routine in the U.S.
In some cases, the M tuberculosis bacterium may not respond to treatment with antibiotics. When people stop their medication too soon or take it incorrectly, bacterial resistance can develop. Some strains of bacteria are multidrug-resistant, which means that at least two first-line drugs are ineffective. Other bacteria strains are extensively drug-resistant or resistant to first- and second-line drugs, which severely limits the likelihood of cure. Drug-resistant TB treatment with antibiotics can last for 20 to 30 months. Untreated TB caused by extensively drug-resistant strains is fatal in 70% of cases.
Your local pharmacist is here to help. If you, a friend, or family member has questions about the risks of TB or about treatments or vaccinations, ask a trusted pharmacist or another healthcare provider.
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