Latent vs Active TB and Testing
Latent TB infection means the client is infected but asymptomatic and non-contagious, with a positive TST or IGRA but a normal chest X-ray, while active TB disease is symptomatic and contagious with an abnormal chest X-ray and positive sputum culture or AFB smear. TST induration cutoffs vary by risk: 5mm is positive in immunocompromised or close contacts of active cases, 10mm in high-risk groups like healthcare workers or recent immigrants from endemic areas, and 15mm in low-risk individuals with no known risk factors. A positive TST doesn't confirm active disease, it only indicates exposure, which the NCLEX tests by requiring chest X-ray and sputum studies for confirmation.
Airborne Precautions
Active pulmonary TB requires airborne precautions: a negative pressure room, N95 or higher respirator for staff (not a standard surgical mask), and the client wears a surgical mask if transported outside the room. Visitors and staff should limit entries and exits to maintain negative pressure. The client can be removed from precautions after three consecutive negative sputum AFB smears on separate days and clinical improvement, showing they are no longer significantly infectious. This specific criterion for discontinuing isolation is a frequently tested detail that differentiates TB from other airborne diseases like measles or varicella.
Medication Therapy and Teaching
First-line TB therapy uses RIPE: rifampin, isoniazid, pyrazinamide, and ethambutol, typically for 2 months, followed by rifampin and isoniazid for an additional 4 months, for a total of at least 6 months. Isoniazid can cause peripheral neuropathy, prevented with vitamin B6 (pyridoxine) supplementation, and hepatotoxicity requires monitoring liver enzymes. Rifampin causes orange-red discoloration of body fluids, which is harmless but should be explained to prevent alarm, and can reduce the effectiveness of oral contraceptives. Ethambutol requires monitoring for optic neuritis with periodic vision checks. Emphasize that stopping treatment early, even when feeling better, is the leading cause of multidrug-resistant TB.