32 Tuberculosis Cupo Flashcards
What is Mycobacterium tuberculosis (MTB)?
Long, thin rods that grow in masses or strands. Composed of complex layer of mycolic acid and waxes. Ziehl-Neelsen acid-fast staining procedure. Obligate AEROBES, non-spore forming, nonmotile. Requires enriched media for growth. Slow growing, multiplying in ever 12-24 hrs. Humans are the only reservoir for infection
What is the transmission of M. tuberculosis like?
Spread by droplet nuclei (< 25 micro-meters in diameter, midlung zones). Expelled when person with infectious TB coughs, sneezes, speaks. Close contacts at higher risk of becoming infected. Transmission occurs from person with infectious TB disease (not latent TB infection)
What are the symptoms of Primary TB?
Fever (not very common). Positive skin test after 4-8 weeks. Chest radiograph: lower zone disease, hilar enlargement (neither are common))
What are the symptoms of Reactivation TB (Pulmonary)?
Common: Cough. Less common: fatigue/malaise, weight loss, night sweats, fever. Tuberculin skin test positive in 85% of patients. Common: Upper zone disease, cavitation
What are some predisposing conditions for TB?
HIV infection and DM (anything with suppressed immunity, these two most common). Silicosis. Prolonged corticosteroid therapy. Other immunosuppressive therapy. Renal insufficiency. Post gastrectomy. Malignant lung or other tumors. Alcoholism. Massive weight loss
What is some general information on Latent TB Infection (LTBI)?
1/3 of the global population are infected w/ M. tuberculosis. ~10% progression to active disease. Progression to active disease greatest in first two years after transmission
What are the characteristics of LTBI?
Inactive TB infection. Patient often doesn’t feel sick. NON-INFECTIOUS. Needs treatment for LTBI to prevent active TB disease. Radiographical studies negative for active disease. Positive TST (skin test) or QST (quantitative skin test)
What are the characteristics of Active TB?
Active TB bacteria infection. Patient feels sick and experiences coughing, fever, and weight loss. Highly infectious. Needs treatment to cure active TB disease. Radiographical studies may be abnormal. TST or QST usually positive. Respiratory specimens may be smear or culture positive
Who are people at higher risk for exposure or infection with TB that should be tested for LTBI?
Close contacts of a person known or suspected to have TB, Foreign-born persons from areas where TB is common, Residents and employees of high risk congregate settings, Health care workers who serve high risk clients, Person who inject illicit drugs
Who are people at higher risk for TB disease once infected that should be tested for LTBI?
Person with HIV infection. Person recently infected with M. tuberculosis. Person with certain medical conditions. Person who injects illicit drugs. Person with a history of inadequately treated TB
What is used for the diagnosis of Latent TB?
Mantoux skin test (PPD). Chest X-Ray. Whole-blood interferon-gamma assay
What is used for the diagnosis of Active TB?
Sputum smear (AFB). Plates/tubes. Bactec system. Difco system. Gene probes (Nucleic acid amplification)
What is the Smear Examination?
Results should be available within 24 hours of specimen collection. Presumptive diagnosis of TB. Increased sensitivity: Light vs. fluorescence microscopy, AFB x3, Induced sputum
What are the characteristics of “Cultures”?
“Gold Standard”. Used to confirm diagnosis of TB. Culture all specimen even if smears are negative. Time to detection depends on the media (anywhere from 13-27 days). Liquid culture systems can detect small amounts of bacterial growth either using radioactivity or by oxygen concentration changes (can also be used for drug susceptibility testing)
What are the characteristics of Drug Susceptibility Testing?
Drug susceptibility testing on initial M. tuberculosis isolate (repeat for patients who do not respond to therapy). Have positive cultures despite 2 months of therapy. Promptly forward results to the health department