Learn the pathophysiology and causes of tuberculosis, identify the risk factors, signs and symptoms, diagnosis, medications, and nursing management for TB.
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Syllabus
Purpose Statement: Upon completion of this module, the learner will be able to discuss the pathophysiology and causes of tuberculosis, identify the risk factors, signs and symptoms, diagnosis, medications, and nursing management for TB.
Objectives
- Define tuberculosis (TB).
- List global concerns related to TB.
- Identify the bacterium that causes TB.
- Explain how TB is spread.
- Describe the differences between latent TB infection and active TB.
- Discuss the signs and symptoms of TB.
- Discuss diagnostic tests specific to TB.
- List the medications used in the treatment of TB.
- Describe the nursing management of TB.
Tuberculosis (TB) is an infectious disease that is caused by Mycobacterium tuberculosis, sometimes called tubercle bacillus. It is an aerobic, gram-positive, acid-fast bacillus. The lungs are the organ most often affected as it is an airborne disease, but TB infection can also impact the bones, kidneys, lymph nodes, or brain. Extrapulmonary TB indicates that the infection has spread somewhere other than the lungs. If a TB infection spreads to multiple sites, it is called military TB. There are two TB-related disorders: latent TB infection (LTBI) and active TB disease. LTBI is when the TB bacteria infect a person, but the body’s immune system is healthy enough to fight the infection and therefore avoid signs and symptoms. Most patients with LTBI will never develop active TB, but will likely have a positive skin or blood test result. TB disease is when the TB bacteria are active in the body with associated signs and symptoms, which makes the patient contagious (Sommers, 2019).
Multidrug-resistant TB (MDR-TB) is a serious health concern. It is defined as resistance to two or more anti-TB drugs, usually when the TB bacteria do not respond with treatment to rifampin (Rifadin) and isoniazid (INH, Niazid). Extensively drug-resistant TB (XDR-TB), when TB bacteria becomes resistant to the second-line treatment drugs, is life-threatening. It is thought that noncompliance with the drug regime, healthcare providers who prescribe incorrect medications, and poor-quality drugs have led to the development of MDR-TB and XDR-TB (WHO, n.d.).
Worldwide, there are more than two billion cases of TB, and about 90% of those patients are unaware that they are infected. TB is found in populations that are experiencing poverty, malnutrition, crowded living or working conditions, and inadequate health care (Bernardo, 2019).
In the US, the 2016 surveillance data indicate a lower TB case count than in previous years (Schmit, Wansaula, Pratt, Price, & Langer, 2017). Additional health promotion strategies are needed to ensure the elimination of this disease. Research suggests that the testing and treatment of LTBI would reduce the incidence of active TB. Currently, it is a requirement for health departments to report verified cases of active TB. Measures to limit the spread of TB in the US include early identification and treatment of active TB as well as identifying all exposed contacts of the TB-infected person. The US Preventive Services Task Force (USPSTF) recommended screening for LTBI in patients at risk for TB in 2016 (Schmit et al., 2017).
Living in or traveling to a high-risk country increases the risk of exposure to TB. The World Health Organization (WHO, 2018) maintains a list of countries with increased TB prevalence, including China, India, the Philippines, and Vietnam. Testing for LTBI is strongly encouraged for potential exposure to TB. High-risk racial or ethnic groups with a higher rate of TB include Hispanics, African Americans, Pacific Islanders, Asians, and Native Americans. Other risk factors for TB include exposure in a high-risk setting, such as correctional facilities, long term care facilities, homeless shelters, or colleges. Anyone living or working in tight quarters is at risk if another resident has active TB disease. Employees at these locations are also at increased risk. Immunocompromised individuals, those who have received chemotherapy, organ recipients, chronic renal failure patients, or those with human immunodeficiency virus (HIV), are at increased risk for developing TB. People with substance abuse, anyone without adequate healthcare, and children less than five-years-old have a higher probability of acquiring TB. Healthcare workers are also at increased risk for TB exposure (WHO, 2018).
The Disease Process
TB, transmitted by airborne respiratory droplets, can spread when a TB-infected person talks, sneezes, coughs, or laughs (Schmit et al., 2017). TB infection then occurs when a person inhales the TB bacteria. The mycobacteria are transmitted through the airways to the lung tissue. The bacteria multiply in this oxygen-rich environment. TB causes damage to pulmonary tissues resulting in inflammation and necrosis, possibly leading to respiratory failure if not treated. In an otherwise healthy patient, the bacteria’s presence triggers the inflammatory cascade, and phagocytes consume the bacteria. There may be an accumulation of fluid in the airways from the exudate. The person may experience some signs of infection approximately 2-10 weeks after exposure. The macrophages surround the TB bacteria and form a granuloma which turns into a fibrous tissue mass or Ghon tubercle. It calcifies and is walled off by the immune system, so there is no further progression of the TB disease. The Ghon complexes are often seen on chest x-rays. While the immune system remains healthy, TB may never become active again in this person. This patient has LTBI, meaning their body is suppressing the disease, and they will not have signs or symptoms of TB and are not contagious. However, LTBI can turn into active TB disease if the immune system is suppressed in some way. Medications may be prescribed to treat LTBI and prevent the development of active TB. TB bacteria can spread to other areas of the body by the lymph system and blood (Sommers, 2019).
Active TB patients have symptoms and can easily infect others via airborne transmission. Active TB typically occurs because of a weakened immune system. Of those initially infected, 10% will develop the active disease. It is important to remember that while TB is contagious, it is also curable with the right treatment (The Centers for Disease Control and Prevention [CDC], 2016).
Signs and Symptoms
TB patients usually present to their healthcare provider with complaints of low-grade fever, night sweats, fatigue, weight loss, chills, productive or nonproductive cough, and hemoptysis (bloody or blood-stained sputum) for several weeks to a month. An older adult may have more insidious signs and symptoms, such as unusual behavior or altered mental status. Patients with reactivated LTBI often report chest pain, low-grade fever, and cough, often with hemoptysis or mucopurulent sputum (Hinkle & Cheever, 2017).
Nursing care of the TB patient starts with early recognition. In the hospital setting, the nurse should place the patient suspected of having TB in a negative pressure room and have the patient wear a surgical mask outside of their room. The nurse completing the health assessment should ask about travel, exposure to TB-infected persons, previous history of testing positive for TB, and other risk factors. The nurse should perform a physical examination, specifically focusing on the respiratory system. Assess the lungs for consolidation by palpating for fremitus and auscultating bilaterally for egophony and breath sounds. Breath sounds may sound diminished or wet with crackles (Schiffman, 2019). Bronchial breath sounds, wheezes, or even whispered pectoriloquy might also be heard on assessment. Chest percussion may elicit a dullness over the area affected, which may signify consolidation or pleural fluid (Hinkle & Cheever
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, 2017). The healthcare provider may order a chest X-ray which may reveal upper lobe lesions. Additional tests may include a skin test, blood tests, or sputum culture for acid-fast bacilli (Schiffman, 2019).
Diagnosis
According to Bernardo (2019), diagnostic testing for TB may include a Mantoux tuberculin skin test (TST or PPD), interferon gamma release assay (IGRA), sputum acid-fast bacilli (AFB) smear, or culture from the bodily fluids. The most definitive test is the isolation of M. tuberculosis from a sample of bodily secretions such as a sputum culture or bronchoalveolar lavage. Radiographic studies may also be used to support the diagnosis (Bernardo, 2019).
The Mantoux TST (see Figure 1 below) is commonly used to detect LTBI. Healthcare providers should have additional training on the administration and interpretation of the results. The test is performed by using a 26 or 27-gauge needle to inject 0.1 ml or five tuberculin units of purified protein derivative (PPD) intradermally. It is critical to use a TB syringe and not an insulin syringe to ensure the correct dose. The test is usually performed on the anterior (palmar) surface of the forearm, approximately 2-4 inches below the elbow. The intradermal injection is given with the needle bevel pointing upwards to create a well-demarcated wheal that is 6-10 mm in diameter. The nurse should document the site, antigen name, strength, lot number, date, and time of testing.
The injection site is examined within 48-72 hours by a trained healthcare provider. Erythema is usually present upon recheck. Any induration (palpable, hardened area) is measured, and the test will be deemed either positive or negative based on the induration size at the widest part. Indurations of 0-4 mm are not significant. An induration of 5 mm or more may be significant if the person is at high risk for TB. Patients with known HIV or a close exposure with a TB-infected person are considered positive at that point. If the induration is 10 mm or more, this indicates a positive result in any patient. A positive test result may indicate past exposure to M. tuberculosis or prior BCG vaccination. Some areas of the world, such as Europe, routinely give BCG vaccinations, but it is not regularly used in the US. The CDC (2011) recommends healthcare providers consult the TB control program in their area before administering the BCG vaccine. If a suspected TB patient needs diagnostic testing and has been vaccinated in the past, then a blood test to detect TB should be used as these are not be affected by prior vaccination and are less likely to give a false-positive result. The nurse should educate the patient that a positive TST result may not mean the patient has active TB, but instead indicate a history of BCG vaccination or LTBI.
Conversely, a negative TST does not exclude TB infection or disease if the person is immunosuppressed. They may not have an adequate immune system response required to produce a positive result. Further evaluation is needed to determine if TB is active or latent (Hinkle & Cheever, 2017).
IGRA is the term used for testing the patient’s blood test for a TB infection. According to the CDC (2016), IGRA blood tests are also known by trade names: T-Spot, TB QuantiFERON-TB Gold (QFT-G), QuantiFERON-TB Gold Plus, and QuantiFERON-TB Gold-In-Tube (QFT_ZGIT). The test results are usually available in less than 24 hours, and the Bacilli Calmette-Guerin (BCG) vaccine does not affect the results of an IGRA blood test. However, the IGRA blood test will indicate a positive result for both active and latent TB. Different strains of the Mycobacterium species may also cause a false-positive test result. It takes approximately six weeks for the patient to test positive with the IGRA blood tests. False negatives are possible if the patient is tested prior to six weeks, so the healthcare provider may order a repeat test. An acid-fast bacilli (AFB) smear will assist in establishing the active TB diagnosis versus latent TB (Bernardo, 2019).
Sputum smears or microscopy utilize an acid-fast bacilli (AFB) smear during which the sputum is examined under a microscope after being stained and washed in an acid solution. The AFB is considered one of the most rapid, inexpensive tests for diagnostic testing. The AFB test requires approximately three milliliters of sputum for the test. AFB presence does not confirm a TB diagnosis, and the sputum sample must be sent for culture and sensitivity testing to confirm the diagnosis. Sputum cultures will provide additional information besides the positive confirmation of TB. Drug susceptibility and drug resistance are identified using sputum cultures. It is recommended that all persons with a positive culture for M. tuberculosis have drug sensitivity and resistance testing. Bronchoscopy may be used if the patient cannot produce an adequate sputum culture (Sommers, 2019).
NAA testing nucleic acid amplification (NAA) can detect Mycobacterium tuberculosis bacteria in the person’s sputum earlier than the sputum culture. Research indicates a greater positive predictor value (>95%) for NAA testing than the AFB smear. However, the sputum culture remains the most sensitive to TB testing. The NAA results must be used in conjunction with other tests for TB to be considered diagnostic. It cannot be used to monitor treatment since the test will remain positive after treatment. It may be used to determine if respiratory isolation should be discontinued on suspected TB patients in the healthcare setting. The NAA test is more expensive than some of the other diagnostic tests and remains a factor when the healthcare provider requests diagnostic testing (Bernardo, 2019).
Supportive diagnostic testing for TB can involve a chest x-ray to assess for nodular lesions, infiltrates, scar tissue, or calcium deposits. These are typically found in the upper lobes. Computed tomography (CT) or magnetic resonance imaging (MRI) scans can aid in evaluating tissue damage or assist in confirming a diagnosis (Sommers, 2019).
Tuberculosis is a reportable disease to the state-controlled TB offices. If a patient is identified with confirmed or suspected active TB disease, it is required by law that the information must be communicated within one day of identification. Any patients diagnosed with extrapulmonary TB or who have started empiric multidrug therapy should be reported to the health department. The public health department in the community then notifies the state health department. State health departments report all TB infections to the CDC, along with the culture specimen (Bernardo, 2019).
During testing, the nurse should provide the patient with information regarding each test (WHO, 2018). Allow the patient an opportunity to ask questions or express concerns regarding the diagnostic process. The nurse should check renal function and ask about allergies to shellfish or iodine if a CT scan with contrast will be done. If the patient is scheduled for an MRI, the nurse should remind the patient not to wear any metal objects during the test and should ask about any metal implants. Informed consent will be needed for a bronchoscopy (Sommers, 2019).
Treatment
Medical management for pulmonary TB includes anti-TB medications. The medication regime may last anywhere from six months to one year. Noncompliance with medication is cited as one of the main reasons for the development of drug-resistant TB. Primary drug resistance is defined as resistance to one of the first-line anti-TB drugs in people who have never been treated for TB. Acquired or secondary drug resistance is defined as resistance to one or more anti-TB medications. Multidrug resistance is defined as resistance to two or more of the first-line TB medications, usually isoniazid (INH, Niazid) and rifampin (Rifadin) (Sommers, 2019).
Five drugs are recognized as first-line medications for TB. They are isoniazid (INH), rifampin (Rifadin), ethambutol (Myambutol), pyrazinamide (PZA) and streptomycin (Agrept). RIPES or STRIPE are two mnemonics that may be useful to remember the most commonly prescribed drugs for TB. Second-line medications include capreomycin (Capastat), ethionamide (Trecator), and cycloserine (Seromycin) (Sommers, 2019).
The nurse should educate the patient that rifampin (Rifadin) should be taken on an empty stomach and warn them that the medication tints body secretions either an orangish or reddish color. The patient should not wear soft contact lenses to avoid staining of the lenses. Rifampin (Rifadin) may decrease the effectiveness of oral contraceptives, so different contraceptive methods should be discussed with female patients of childbearing age (Frandsen & Pennington, 2018).
Isoniazid (INH Niazid) is the most commonly used drug for TB. Patients with a positive TST may be given isoniazid (INH, Niazid) to prevent the development of active TB disease. It is usually given with vitamin B6 (pyridoxine) to prevent neuritis. It is often combined with rifampin (Rifadin) in the combination Rifamate for ease of use. The nurse should monitor the patient for side effects such as peripheral neuromyopathy and liver damage. Education should include instructing the patient to contact the healthcare provider if they develop yellow sclera or a yellow tint to the skin or any symptoms of peripheral neuropathy or numbness. The nurse should instruct the patient to avoid consuming alcohol due to drug interactions (Frandsen & Pennington, 2018).
Pyrazinamide (PZA) is often used with isoniazid (INH, Niazid) and rifampin (Rifadin) for the first few months of active TB. For this reason, the triple combination drug Rifater was created by Sanofi-Aventis for ease of use. PZA has a bactericidal effect by lowering the intracellular pH. It can increase uric acid levels. Gastrointestinal upset often occurs if the patient does not take it with food. The most significant adverse effect is liver impairment, so it is necessary to monitor liver enzymes regularly during treatment. The nurse should educate the patient on the signs of liver dysfunction and the need for follow-up liver enzymes. Specific indications of liver dysfunction may include abdominal pain and edema in the abdomen, ankles, or legs. The patient may complain of itchy skin, dark urine color, or pale, bloody, or tar-colored stools. Nausea, vomiting, and chronic fatigue often occur with liver issues. The patient may appear jaundiced in the sclera or skin. Pyrazinamide (PZA) may also increase exacerbations of gout by inhibiting urate excretion (Frandsen & Pennington, 2018; Sommers, 2019).
Ethambutol (Myambutol) is often used with active TB. It stops RNA synthesis and is considered bacteriostatic. It prevents TB bacteria from replicating. Ethambutol (Myambutol) may inflame the optic nerve so the patient will require regular eye exams. The nurse should warn the patient that they may experience changes in color perception and discrimination with the potential for blindness. The patient should have a baseline eye exam with an optometrist with regular follow-up visits during treatment. Young patients whose visual acuity cannot be measured should not take ethambutol (Myambutol) (Frandsen & Pennington, 2018).
Streptomycin (Seromycin), an aminoglycoside, interrupts and stops protein synthesis and kills bacteria. It can cause ototoxicity, and the nurse should be sure to ask the patient about any tinnitus. Nephrotoxicity can also occur with aminoglycosides, so the nurse should be sure that kidney function is monitored throughout treatment (Yttri & Zuckerman, 2013).
Fixed-dose combination (FDC) is when two or more drugs are combined to make one tablet for treatment. Rifampin and isoniazid (Rifamate) and rifampin, isoniazid, and PZA (Rifater) mentioned above are examples of FDA-approved FDC. One example of a four-drug FDC treatment used globally for TB is Rimstar 4-FDC, which combines rifampin, isoniazid, PZA, and ethambutol. These types of drugs are often used with diseases such as TB or HIV to simplify and thus enhance compliance with the medication regime. Several advantages are noted with using FDC combinations and include reduced costs associated with multiple medications, less chance of medication error, and increased patient satisfaction with only taking one medication as opposed to multiple different medications. Secondary drugs are used when the primary drugs are contraindicated, or culture and sensitivity testing indicate resistance to the first-line drugs. Persons infected with HIV, pregnant patients, or young children have additional considerations when prescribing TB medication and treatment (WHO, n.d.).
Nursing management regarding TB medications includes education on the importance of medication adherence and signs of medication toxicity and monitoring laboratory testing. For example, sputum cultures will need to be followed to make sure the bacteria are sensitive to the planned medication treatment, which may take days to weeks. Modifications to the drug regime may be required based on these results. Clinical monitoring and laboratory monitoring are necessary to ensure the safe delivery of TB medications. Nurses play an essential role in patient education. All the patient’s pre-existing medications should be reviewed for possible interactions with TB medications, including any over the counter or herbal medicines. The nurse must discuss topics such as potential adverse drug effects, signs of liver dysfunction, dietary measures, and activity levels. Laboratory monitoring for liver function is needed before beginning medications, with repeat labs as indicated or prescribed by the healthcare provider. If patients are not compliant with their medication(s), they should be referred for directly observed therapy (DOT). A designated person, often a healthcare worker, watches the patient take their prescribed medication(s) (Sommers, 2019).
Nursing Management
Nursing concepts identified with TB-infected patients are infection control, oxygenation, nutrition, and education. Patients suspected of having TB or diagnosed with active TB will require airborne isolation precautions. Healthcare providers and hospital personnel should review and adhere to hospital policies for TB-infected patients. Airborne isolation is used when the droplets are 5µm or less in size and may be spread over distances greater than 10 feet. Negative pressure rooms are necessary to prevent the TB droplets from spreading when someone exits the door. A properly fitted N95 respirator should be worn by anyone entering the isolation room to avoid the inhalation of the airborne pathogens. Anyone entering the patient’s room should practice good handwashing and proper disposal of personal protection equipment (PPE). The patient will need to be in isolation for two to three weeks or until noninfectious (Thompson, 2017). The patient is not considered contagious if they meet three criteria established by the CDC. First, the patient should have three consecutive negative AFB sputum smears. The specimens are obtained in 24-hour intervals or per hospital protocol. At least one sputum specimen is collected in the morning. The second criterion is that the patient has been taking the prescribed anti-tuberculin medication regimen for two weeks or longer. The third criterion to be considered non-contagious is that the patient is no longer symptomatic. The CDC recommends that patients meet all three criteria before they are deemed noninfectious (CDC, 2016a).
The patient may experience inadequate gas exchange and ineffective airway clearance due to the copious secretions. The patient should be directed on respiratory hygiene practices such as covering their nose and mouth with a tissue when coughing and proper disposal of used tissues in a covered container. The patient will need instruction on the importance of coughing, deep breathing, and postural drainage. The nurse should encourage hydration to thin respiratory secretions and administer expectorants as directed (Sommers, 2019).
A dietary consult would be very beneficial for a TB patient. They may be at risk for imbalanced nutrition, so weight should also be monitored. Small, frequent, high-calorie meals should be offered to the patient. Some of the TB medications such as isoniazid (INH) should be given with food to prevent gastrointestinal disturbances (Sommers, 2019).
Fatigue is a concern for TB patients. The nurse should ensure that the patient has ample opportunity to rest in a quiet environment. Physical activity should also be encouraged, but with frequent rest periods. The goal is to promote health while conserving energy to reduce oxygen demand (Sommers, 2019).
The nurse should stress the importance of following up regularly with their healthcare provider. The primary concern with the rising number of patients with LTBI is noncompliance with the medication regimen. Laboratory tests will need to be obtained and monitored throughout treatment due to the potential adverse effects of the medication regimen. The patient may also benefit from joining a support group through the American Lung Association or similar (Sommers, 2019).
During discharge planning, resources within the patient’s community need to be considered and discussed with the healthcare team. Home health nursing may be indicated to monitor medication compliance, educate the patient and family members on TB prevention, and obtain specimens for follow-up laboratory testing (Sommers, 2019).
Evidence-based nursing practice/implications for nursing
The CDC and National Tuberculosis Controllers Association updated recommendations on May 17, 2019, for healthcare personnel (HCP) and volunteers. The new guidelines for baseline screening and testing include TB screening for all HCP, including symptom evaluation, either an IGRA or tuberculin skin test (TST) for HCP without documented prior TB disease or LTBI and an individual TB risk assessment. Health care personnel with LTBI and no previous treatment should be strongly encouraged to complete treatment with a recommended regimen, including short-course treatments unless contraindicated. For postexposure screening and testing, the new recommendations are for a symptom evaluation for exposed HCPs. If an HCP with a previous negative baseline TB test and no prior TB disease or LTBI is detected, then an IGRA or TST should be performed. Another test is recommended in 8-10 weeks if the first test is negative. Serial screening and testing for HCP without LTBI are not routinely recommended for those working in low-risk health care settings but should be considered for moderate-risk health care settings (Sosa et al., 2019). TB education is recommended for all HCP annually with an emphasis on TB exposure risks (Hinkle & Cheever, 2017).
Future research/directions
Tuberculosis Epidemiologic Studies Consortium II (TBESC-II) is partnering with the Division of Tuberculosis Elimination (DTBE), academic institutions, and TB control programs in 11 states focusing on LTBI in high-risk populations. The focus is on strategies and tools to increase diagnosis and treatment for LTBI. According to mathematical models, identification and treatment will have the largest impact on TB elimination in the US. Identified barriers are a lack of a gold standard test for LTBI, insufficient surveillance, and a lack of proven methodologies to identify and treat high-risk groups (CDC, 2016a).
Tuberculosis Trials Consortium (TBTC) was created and formalized in 1997 to focus on tuberculosis research, treatments, and medications and now is international in scope. Great strides have been made with recommendations for shortening medication regimens based on their research findings (CDC, 2016a).
References
The Centers for Disease Control and Prevention (2011). Vaccine and Immunizations: TB Vaccine (BCG). Retrieved from https://www.cdc.gov/tb/topic/vaccines/
The Centers for Disease Control and Prevention (2016a). Basic TB Facts. Retrieved from https://www.cdc.gov/tb/topic/basics/default.htm
The Centers for Disease Control and Prevention (2016b). Testing for TB Infection [images]. Retrieved from https://www.cdc.gov/tb/topic/testing/tbtesttypes.htm
Frandsen, G., & Pennington, S. (2018). Abrams’ clinical drug therapy: Rationales for nursing practice. Philadelphia, PA. Lippincott Williams & Wilkins.
Hinkle, J., & Cheever, K. (2017). Brunner & Suddarth’s textbook of medical-surgical nursing. Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins.
Schiffman, G. (2019). Tuberculosis Symptoms. Retrieved from http://www.emedicinehealth.com/tuberculosis/page3_em.htm
Schmit, K. M., Wansaula, Z., Pratt, R., Price, S. F., & Langer, A. J. (2017). Tuberculosis –
United States, 2016. MMWR. Morbidity and Mortality Weekly Report, 66(11), 289–
294. doi:10.15585/mmwr.mm6611a2
Sommers, M. (2019). Davis’s diseases & disorders a nursing therapeutics manual (6th ed.). Philadelphia, PA: F. A. Davis.
Sosa L. E., Njie G. J., Lobato M. N., Bamrah, S., Morris, Buchta, W.,… Belknap, R. et al. (2019). Tuberculosis screening, testing, and treatment of U.S. health care personnel: Recommendations from the National Tuberculosis Controllers Association and CDC. MMWR Morb Mortal Wkly Rep 68(19) 439–443. doi: 10.15585/mmwr.mm6819a3.
Thompson, M. (2017). Save a Life. Retrieved from https://nhcps.com/a-nurses-guide-to-isolation-precautions/
The World Health Organization (n.d.). Drug-resistant TB: XDR-TB FAQ. Retrieved July 28, 2019 from https://www.who.int/tb/areas-of-work/drug-resistant-tb/xdr-tb-faq/en/
The World Health Organization (2018). Tuberculosis. Retrieved from http://www.who.int/mediacentre/factsheets/fs104/en/index.html
Yttri, J., & Zuckerman, D. (2013). Antibiotics: When science and wishful thinking collide.
Health Affairs. Health Affairs Blog. doi: 10.1377/hblog20130125.027503