In this article, we'll explain tuberculosis (TB), including the definition, pathophysiology, labs and diagnostics, treatment, and nursing care, to help you prepare for the NCLEX and for your Med-Surg exams.
The Med-Surg Nursing video series follows along with our Medical-Surgical Nursing Flashcards, which are intended to help RN and PN nursing students study for nursing school exams, including the ATI, HESI, and NCLEX.
What is tuberculosis?
Tuberculosis, or TB, is an infectious disease of the lungs that is caused by Mycobacterium tuberculosis.
The mode of tuberculosis transmission is airborne — the organism (bacteria) is transmitted via aerosolization and attaches to the alveoli in the lungs. This triggers an immune response, the ingestion of the bacilli by macrophages, and the development of granulomas, or lesions, in the lungs. Macrophages are cells responsible for detecting, engulfing, and destroying pathogens; they play a role in alerting the immune system to the presence of invaders.
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Signs and symptoms
Symptoms of tuberculosis can include a cough that lasts for more than three weeks, purulent (pus) or bloody sputum, unexplained weight loss, night sweats, and lethargy.
Note that these are the symptoms that all patients are screened for at the hospital during admission to establish if they may have tuberculosis. If they answer "yes" to the symptoms listed above, they are put on airborne precautions until tuberculosis can be ruled out.
Labs and diagnostics
In terms of diagnostics related to tuberculosis, there are a number of labs that may be run, including the quantiferon gold blood test, the mantoux skin test, an acid-fast bacilli culture, and a chest x-ray.
QuantiFERON Gold blood test
A quantiferon gold blood test is a simple blood test that aids in the detection of Mycobacterium tuberculosis.
Mantoux skin test
A Mantoux skin test is an intradermal injection, read within 48 – 72 hours, that checks for induration (hardening) at the site. An induration of 10 mm is a positive result, that is, the patient either has an active TB infection or had a previous infection with tuberculosis. For immunocompromised patients, 5 mm is a positive result. This is because an immunocompromised patient's body isn't able to mount enough of an immune response to get a 10 millimeter area of induration.
Note that patients who have lived internationally and have received a BCG vaccine (Bacillus Calmette-Guérin vaccine, primarily used against tuberculosis) may show a false positive result.
Acid-fast bacilli culture
Acid-fast bacilli (AFB) testing is the process of inoculating a clinical specimen onto culture media, then examining it for bacterial growth. When taking samples for this test, use three early morning sputum samples.
Chest x-ray
A chest x-ray may be used to check for the presence of active lesions in the lungs.
Treatment
Treatment of tuberculosis includes a combination drug therapy. Patients will take up to four antibiotics for a period of 6 – 12 months.
The medications commonly used to treat TB include rifampin, isoniazid, pyrazinamide, and ethambutol. A handy mnemonic for this quartet is "ripe orange." The letters “r” “i” “p” “e” match the first letters of the four medications, and "orange" refers to the orange discoloration of secretions expected with rifampin use.
Nursing care
In terms of nursing care for a patient with tuberculosis, place them in a negative airflow room, because they will be on airborne precautions. Anyone entering the room should wear an N-95 mask. And if the patient must leave their room, they should wear a surgical mask. This is to protect the patient or people entering the patient’s room.
Screen the patient's family for TB because it is an extremely contagious disease.
Teach the patient that throughout their therapy, they will have to provide a sputum sample every few weeks. Patients are no longer considered infectious after three negative sputum cultures.