Tuberculosis: Testing, Isolation and Drugs

Medical-Surgical · Respiratory / Pulmonology·Updated 2026-10-28

What it is

Tuberculosis (TB) is infection with Mycobacterium tuberculosis, spread by airborne droplet nuclei when a person with active pulmonary or laryngeal TB coughs, speaks or sneezes. Most infected people have latent TB infection: no symptoms, not contagious, but able to reactivate when immunity falls (HIV, older age, corticosteroids, TNF inhibitors). The airborne spread and the slow-growing, easily resistant organism explain the care: airborne isolation until noninfectious and months of multidrug therapy taken without gaps.

What the NCLEX focuses on

Active TB: cough lasting 3 weeks or longer, hemoptysis, night sweats, low-grade afternoon fever, fatigue, anorexia and weight loss.
Tuberculin skin test (TST): read induration, not redness, at 48 to 72 hours; positive is 5 mm or more (HIV, immunosuppression, recent contact), 10 mm or more (health care workers, recent arrivals from high-prevalence countries, injection drug use, congregate settings) or 15 mm or more (no risk factors).
Interferon-gamma release assay (IGRA): a one-visit blood test not affected by previous BCG vaccine.
A positive TST or IGRA shows infection, not active disease; chest x-ray and three sputum specimens for acid-fast bacilli (AFB) smear and culture confirm active TB.
Airborne precautions: negative-pressure airborne infection isolation room with the door closed, fit-tested N95 respirator for staff, surgical mask on the client outside the room.
Drug-susceptible TB: rifampin, isoniazid, pyrazinamide and ethambutol for 2 months, then rifampin and isoniazid for 4 months, given by directly observed therapy (DOT).
Toxicities: isoniazid, rifampin and pyrazinamide are hepatotoxic; isoniazid causes peripheral neuropathy (prevented with pyridoxine); rifampin turns body fluids orange-red and weakens hormonal contraceptives; ethambutol causes optic neuritis (red-green color loss); pyrazinamide raises uric acid.

Priority nursing actions

Place a surgical mask on the client with suspected TB and move the client to an airborne infection isolation room with the door closed.
Wear a fit-tested N95 respirator for every room entry.
Collect three sputum specimens as prescribed, at least one early in the morning.
Obtain baseline liver function tests and vision testing, then start the multidrug regimen.
Report the case to public health and coordinate DOT and contact investigation.

Numbers to know

Value	Standard	Why it matters
TST read time	48 to 72 hours after placement	Measure induration only
TST positive cutoffs	5 mm, 10 mm or 15 mm by risk group	Higher-risk clients need a smaller reaction
Sputum specimens	3, at least one early morning	Confirm disease and track infectiousness
Treatment length (drug-susceptible)	6 months: 2 months of 4 drugs, 4 months of 2	Stopping early causes relapse and resistance
Isolation room air changes	At least 6 per hour (12 in new construction)	Removes droplet nuclei from the room
Ending isolation	3 negative AFB smears, effective therapy, clinical improvement	Client is no longer infectious

Common exam traps

Choosing a surgical mask for the nurse entering the room: wrong because only a fit-tested N95 or higher respirator filters droplet nuclei.
Choosing to have the client wear an N95 respirator during transport: wrong because the client wears a surgical mask to contain secretions.
Choosing to keep the isolation room door open for airflow: wrong because it breaks the negative-pressure seal.
Choosing to stop the drugs once symptoms improve: wrong because incomplete therapy causes relapse and multidrug-resistant TB.
Choosing to report orange-red urine as an allergic reaction: wrong because it is an expected, harmless effect of rifampin.

What to teach

Take every dose for the full course, usually observed by a health care worker; never skip doses because you feel better.
Avoid alcohol; report dark urine, yellow skin or eyes, nausea or right upper abdominal pain, numbness or tingling, and any change in vision.
Rifampin stains urine, sweat, tears and soft contact lenses orange-red and makes hormonal birth control less effective; use a backup or nonhormonal method.
Cover coughs, bag used tissues, and stay home from work or school until cleared.

Client handout: Treating Tuberculosis (TB) (nurse guide and printable patient handout).

Try 2 NCLEX-style questions on this topic

From the NCLEXPace question bank. Pick your answers, then check them inside NCLEXPace.

Question 1 · QID E434D60E

A client is admitted with a three-week productive cough, night sweats, and a 6.8 kg (15 lb) weight loss, and pulmonary tuberculosis is suspected. Which actions should the nurse take?

Select all that apply.

A. Keep the room door open to improve airflow
B. Explain that drug therapy continues for 6 to 9 months
C. Place the client in a negative-pressure isolation room
D. Teach that rifampin turns urine and tears orange
E. Wear a fit-tested N95 respirator when entering the room
F. Have the client wear an N95 respirator during transport

Question 2 · QID BBFA58BD

A client starting isoniazid for active tuberculosis asks why pyridoxine (vitamin B6) has also been prescribed. Which explanation is accurate?

Select the best answer.

A. "The vitamin is optional unless you begin having numbness or tingling, because it is mainly added after nerve symptoms develop."
B. "Isoniazid depletes vitamin B6, and taking it helps prevent nerve damage."
C. "Pyridoxine prevents the orange-red discoloration of urine and tears that can occur during tuberculosis treatment."
D. "Pyridoxine works as an additional tuberculosis medication that strengthens the antimicrobial effect of isoniazid."

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Sources

Harding MM, Kwong J, Hagler D, Reinisch C. Lewis's Medical-Surgical Nursing: Assessment and Management of Clinical Problems. 12th ed. Elsevier; 2023; Chapter: Lower Respiratory Problems.
Nahid P, Dorman SE, Alipanah N, et al. Official American Thoracic Society/Centers for Disease Control and Prevention/Infectious Diseases Society of America Clinical Practice Guidelines: Treatment of Drug-Susceptible Tuberculosis. Clin Infect Dis. 2016;63(7):e147-e195.
Jensen PA, Lambert LA, Iademarco MF, Ridzon R. Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Settings, 2005. MMWR Recomm Rep. 2005;54(RR-17):1-141.

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