Fundamentals of decreased by approximately 5.6% each year - PDF document

Mantoux Tuberculin Skin Test Training Guide TB in the United States • From 1953 to 1984, reported cases Fundamentals of decreased by approximately 5.6% each year Tuberculosis (TB) • From 1985 to 1992, reported cases increased by 20% • 25,313 cases reported in 1993 • Since 1993, cases are steadily declining 1 2 Transmission and Factors Contributing to the Pathogenesis of TB Increase in TB Cases • Caused by Mycobacterium tuberculosis (M. • HIV epidemic tuberculosis) • Increased immigration from high- • Spread person to person through airborne particles prevalence countries that contain M. tuberculosis , called droplet nuclei • Transmission of TB in congregate • Transmission occurs when an infectious person settings (e.g., correctional facilities, long- coughs, sneezes, laughs, or sings term care) • Prolonged contact needed for transmission • Deterioration of the public health care • 10% of infected persons will develop TB disease at infrastructure some point in their lives 3 4

Mantoux Tuberculin Skin Test Training Guide Not Everyone Exposed Sites of TB Disease Becomes Infected • Pulmonary TB occurs in the lungs – 85% of all TB cases are pulmonary • Probability of transmission depends • Extrapulmonary TB occurs in places other than the on: lungs, including the: – Infectiousness – Larynx – Lymph nodes – Type of environment – Pleura (membrane surrounding each lung) – Length of exposure – Brain and spine • 10% of infected persons will develop – Kidneys – Bones and joints TB disease at some point in their lives • Miliary TB occurs when tubercle bacilli enter the bloodstream and are carried to all parts of the body 5 6 Groups at High Risk for Risk Factors for Developing TB TB Exposure Disease Once Infected • Close contacts of a person with infectious TB • HIV infection • Foreign-born persons from areas where TB is • Substance abuse (especially drug injection) common • Recent TB infection/documented recent • Persons who work or reside in high-risk conversion congregate settings • Children < 5 years of age with positive TST • Persons who inject drugs results • Locally identified high-risk groups, such as farm workers or homeless persons • Certain medical conditions 7 8

Mantoux Tuberculin Skin Test Training Guide Medical Conditions that Increase the Latent TB Infection (LTBI) Progression of TB Infection to TB Disease • Certain medical conditions increase the risk that TB infection will progress to disease, including: • Occurs when person breathes in bacteria – HIV infection and it reaches the air sacs (alveoli) of lung – Chest x-ray findings consistent with prior TB (in a person inadequately treated) – Low body weight (10% or more below the ideal) – Silicosis • Immune system keeps bacilli contained – Diabetes mellitus and under control – Chronic renal failure/hemodialysis – Certain intestinal conditions (e.g., jejunoileal bypass, gastrectomy) – Solid organ transplant – Certain types of cancer (e.g., leukemia, cancer of the head and • Person is not infectious and has no neck) – Prolonged therapy with corticosteroids and other symptoms immunosuppressive agents 9 10 LTBI vs. TB Disease TB Disease LTBI TB Disease • Occurs when immune system cannot Tubercle bacilli in the body Tuberculin skin test reaction usually positive keep bacilli contained Chest x-ray usually normal Chest x-ray usually abnormal • Bacilli begin to multiply rapidly Sputum smears and cultures Symptoms smears and cultures negative positive No symptoms Symptoms such as cough, fever, • Person develops TB symptoms weight, loss Not infectious Often infectious before treatment Not a case of TB A case of TB 11 12

Mantoux Tuberculin Skin Test Training Guide Groups to Target with the Targeted Testing Tuberculin Skin Test • Persons with or at risk for HIV infection • Only at risk persons should be • Close contacts of persons with infectious TB routinely tested for TB • Persons with certain medical conditions • Injection drug users • Testing should be done only if there • Foreign-born persons from areas where TB is common • Medically underserved, low-income populations is an intent to treat • Residents of high-risk congregate settings • Locally identified high-prevalence groups 13 14 Administering the Tuberculin Classifying the TST Reaction - 1 Skin Test > 5 mm of induration is positive in: • Use Mantoux tuberculin skin test – HIV-infected persons • 0.1 mL of 5 - U of purified protein derivative T – Close contacts of a person with infectious TB (PPD) solution injected intradermally – Persons who have chest x-ray findings • Read within 48 - 7 2 hours (reading and consistent with prior TB interpretation should be performed by trained – Organ transplant recipients health care worker) – Persons who are immunosuppressed for other • Measure transverse diameter of induration reasons • Record results in millimeters of induration 15 16

Mantoux Tuberculin Skin Test Training Guide Classifying the TST Reaction - 2 Classifying the TST Reaction - 3 > 10 mm induration is positive in: > 15 mm induration is positive in: – Recent immigrants (within last 5 years) from a • All persons with no known risk factors high-prevalence country – Injection drug users (with unknown or HIV- for TB negative status) – Persons with other high-risk medical conditions – Residents/employees of high-risk congregate settings – Mycobacteriology laboratory personnel – Children < 4 years of age, or child or adolescent exposed to adults at high risk 17 18 BCG Vaccination and Tuberculin Classifying the TST Reaction - 4 Skin Test For persons who may have occupational • No reliable way to distinguish tuberculin exposure to TB, the appropriate cutoff skin test reactions caused by bacille depends on: Calmette-Guérin (BCG) vaccine from TB • Individual risk factors for TB infection • The prevalence of TB in the facility or place of • Evaluate all BCG-vaccinated persons employment who have a positive skin test result for treatment of LTBI 19 20

Mantoux Tuberculin Skin Test Training Guide Boosting Anergy • Some people with history of LTBI lose their • The inability to react to the tuberculin skin ability to react to tuberculin test due to weakened immune system • Do not rule out diagnosis of TB on basis of a • Baseline TST result may be negative negative TST result (immune system “forgets” how to react to • Consider anergy in non-reactors who: TB-like substance, i.e., PPD) – Are immunocompromised (e.g., HIV-infected, undergoing chemotherapy) • Later TST result will be positive (baseline – Have overwhelming TB disease test stimulated/ “boosted” body’s immunologic memory) 21 22 Two-Step Testing - 1 Two-Step Testing - 2 Baseline TST • A strategy for differentiating between boosted reactions and reactions caused by Negative Result recent TB infection Repeat TST 1 - weeks later 3 • 2nd skin test given 1-3 weeks after baseline TST • Used in many residential facilities for initial NEGATIVE: POSITIVE: skin testing of new employees who will be re- Person probably does not This is a “ boosted” reaction tested (with single test) on a regular basis have TB infection due to TB infection a long time ago 23 24

Mantoux Tuberculin Skin Test Training Guide Infectiousness - 1 Infectiousness - 2 • Patients are not considered infectious if • Patients should be considered infectious if they meet all these criteria: they: – Are undergoing cough-inducing procedures – Received adequate treatment for 2-3 weeks – Have sputum smears positive for acid-fast bacilli (AFB) – Favorable clinical response to treatment and: • Are not receiving treatment – 3 consecutive negative sputum smears • Have just started treatment, or results from sputum collected on different • Have a poor clinical or bacterial response to treatment days – Have cavitary disease • Extrapulmonary TB patients are not infectious 25 26 Techniques to Decrease TB Evaluation for TB Transmission • Instruct patient to: • Medical history – Cover mouth when coughing or sneezing – Wear mask as instructed • Physical examination – Open windows to assure proper ventilation – Do not go to work or school until instructed by • Mantoux tuberculin skin test physician – Avoid public places • Chest x-ray – Limit visitors – Maintain home or hospital isolation as ordered • Bacteriologic exam (smear and culture) 27 28

Mantoux Tuberculin Skin Test Training Guide Symptoms of TB Chest x-Ray • Productive prolonged cough * • Chest x-ray should be done for patients • Chest pain * with positive skin test results • Hemoptysis * • Fever and chills • Abnormal chest x-ray, by itself, cannot • Night sweats confirm the diagnosis of TB but can be • Fatigue used in conjunction with other diagnostic • Loss of appetite indicators • Weight loss *Commonly seen in cases of pulmonary TB 29 30 Sputum Collection Smear Examination • Sputum specimens are essential to • Strongly consider TB in patients with confirm TB smears containing AFB • Mucus from within lung, not saliva • Collect 3 specimens on 3 different days • Use follow-up smear examinations to • Spontaneous morning sputum more assess patient’s infectiousness and desirable than induced specimens response to treatment • Collect sputum before treatment is initiated 31 32