FundamentalsofTB

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Fundamentals of Tuberculosis (TB): 

1 Fundamentals of Tuberculosis (TB)

TB in the United States: 

2 TB in the United States From 1953 to 1984, reported cases decreased by approximately 5.6% each year From 1985 to 1992, reported cases increased by 20% 25,313 cases reported in 1993 Since 1993, cases are steadily declining

Factors Contributing to the Increase in TB Cases: 

3 Factors Contributing to the Increase in TB Cases HIV epidemic Increased immigration from high-prevalence countries Transmission of TB in congregate settings (e.g., correctional facilities, long term care) Deterioration of the public health care infrastructure

Transmission and Pathogenesis of TB: 

4 Transmission and Pathogenesis of TB Caused by Mycobacterium tuberculosis (M. tuberculosis) Spread person to person through airborne particles that contain M. tuberculosis , called droplet nuclei Transmission occurs when an infectious person coughs, sneezes, laughs, or sings Prolonged contact needed for transmission 10% of infected persons will develop TB disease at some point in their lives

Sites of TB Disease: 

5 Sites of TB Disease Pulmonary TB occurs in the lungs 85% of all TB cases are pulmonary Extrapulmonary TB occurs in places other than the lungs, including the: Larynx Lymph nodes Brain and spine Kidneys Bones and joints Miliary TB occurs when tubercle bacilli enter the bloodstream and are carried to all parts of the body

PowerPoint Presentation: 

6 Not Everyone Exposed Becomes Infected Probability of transmission depends on: Infectiousness Type of environment Length of exposure 10% of infected persons will develop TB disease at some point in their lives 5% within 1-2 years 5% at some point in their lives

Persons at Risk for Developing TB Disease: 

7 Persons at Risk for Developing TB Disease Persons at high risk for developing TB disease fall into 2 categories Those who have been recently infected Those with clinical conditions that increase their risk of progressing from LTBI to TB disease

Recent Infection as a Risk Factor: 

8 Recent Infection as a Risk Factor Persons more likely to have been recently infected include Close contacts to persons with infectious TB Skin test converters (within past 2 years) Recent immigrants from TB-endemic areas (within 5 years of arrival to the U.S.) Children ≤ 5 years with a positive TST Residents and employees of high-risk congregate settings (e.g. correctional facilities, homeless shelters, healthcare facilities)

Increased Risk for Progression to TB Disease: 

9 Increased Risk for Progression to TB Disease Persons more likely to progress from LTBI to TB disease include HIV infected persons Those with history of prior, untreated TB Underweight or malnourished persons Injection drug use Those receiving TNF- α antagonists for treatment of rheumatoid arthritis or Crohn’s disease Certain medical conditions

PowerPoint Presentation: 

10 Latent TB Infection (LTBI) Occurs when person breathes in bacteria and it reaches the air sacs (alveoli) of lung Immune system keeps bacilli contained and under control Person is not infectious and has no symptoms

PowerPoint Presentation: 

11 TB Disease Occurs when immune system cannot keep bacilli contained Bacilli begin to multiply rapidly Person develops TB symptoms

LTBI vs. TB Disease: 

12 LTBI vs. TB Disease LTBI TB Disease Tubercle bacilli in the body TST or QFT-Gold ® result usually positive Chest x-ray usually normal Chest x-ray usually abnormal Sputum smears and cultures negative Symptoms smears and cultures positive No symptoms Symptoms such as cough, fever, weight, loss Not infectious Often infectious before treatment Not a case of TB A case of TB

Targeted Testing: 

13 Targeted Testing Detects persons with LTBI who would benefit from treatment De-emphasize testing of groups of people who are not at risk (mass screening) Consider using a risk assessment tool Testing should be done only if there is an intent to treat Can help reduce the waste of resources and prevent unnecessary treatment

Groups to Target with the Tuberculin Skin Test: 

14 Groups to Target with the Tuberculin Skin Test Persons with or at risk for HIV infection Close contacts of persons with infectious TB Persons with certain medical conditions Injection drug users Foreign-born persons from areas where TB is common Medically underserved, low-income populations Residents of high-risk congregate settings Locally identified high-prevalence groups

Administering the TST: 

15 Administering the TST Use Mantoux tuberculin skin test 0.1 mL of 5-TU of purified protein derivative (PPD) solution injected intradermally Use a 27 gauge needle Produce a wheal that is 6-10mm in diameter

Reading the TST: 

16 Reading the TST Read within 48-72 hours Measure induration, not erythema Positive reactions can be measured accurately for up to 7 days Negative reactions can be read accurately for only 72 hours

TST Interpretation - 1 : 

17 TST Interpretation - 1 5 mm of induration is positive in: HIV-infected persons Close contacts to an infectious TB case Persons who have chest x-ray findings consistent with prior untreated TB Organ transplant recipients Persons who are immunosuppressed (e.g., those taking the equivalent of >15 mg/d of prednisone for 1 month or those taking TNF- α antagonists)

TST Interpretation - 2 : 

18 TST Interpretation - 2 10 mm induration is positive in: Recent immigrants (within last 5 years) from a high-prevalence country Injection drug users Persons with other high-risk medical conditions Residents or employees of high-risk congregate settings Mycobacteriology laboratory personnel Children < 4 years of age; infants, children, and adolescents exposed to adults at high risk

TST Interpretation - 3 : 

19 TST Interpretation - 3 15 mm induration is positive in: Persons with no known risk factors for TB

Recording TST Results: 

20 Recording TST Results Record results in millimeters of induration, not “negative” or “positive” Only trained healthcare professionals should read and interpret TST results

False Positive TST Reactions: 

21 False Positive TST Reactions Nontuberculous mycobacteria Reactions are usually ≤10mm of induration BCG vaccination Reactivity in BCG vaccine recipients generally wanes over time Positive TST results is likely due to TB infection if risk factors are present BCG-vaccinated persons with positive TST result should be evaluated for treatment of LTBI QFT is able to distinguish M.tb from other mycobacteria and BCG vaccine

False Negative TST Reactions: 

22 False Negative TST Reactions Anergy, or inability to react to TST because of weakened immune system Recent TB infection (2-10 weeks after exposure) Very young age (newborns) Recent live-virus vaccination can temporarily suppress TST reactivity Poor TST administration technique (too shallow or too deep, or wheal is too small)

Boosting: 

23 Boosting Some people with history of LTBI lose their ability to react to tuberculin (immune system “forgets” how to react to TB-like substance, i.e., PPD) Initial TST may stimulate (boost) the ability to react to tuberculin Positive reactions to subsequent tests may be misinterpreted as new infections rather than “boosted” reactions

Two-Step Testing - 1: 

24 Two-Step Testing - 1 A strategy for differentiating between boosted reactions and reactions caused by recent TB infection Use two-step testing for initial (baseline) skin testing of adults who will be re-tested periodically 2 nd skin test given 1-3 weeks after baseline

Two-Step Testing - 2: 

25 Two-Step Testing - 2 If the 1 st TST is positive, consider the person infected If the 1 st TST is negative, administer 2 nd TST in 1-3 weeks If the 2 nd TST is positive, consider the person infected If the 2 nd TST is negative, consider the person uninfected at baseline

Infectiousness - 1 : 

26 Infectiousness - 1 Patients should be considered infectious if they: Are undergoing cough-inducing procedures Have sputum smears positive for acid-fast bacilli (AFB) and: Are not receiving treatment Have just started treatment, or Have a poor clinical or bacterial response to treatment Have cavitary disease Extrapulmonary TB patients are not infectious

Infectiousness - 2 : 

27 Infectiousness - 2 Patients are not considered infectious if they meet all these criteria: Received adequate treatment for 2-3 weeks Favorable clinical response to treatment 3 consecutive negative sputum smears results from sputum collected on different days

Techniques to Decrease TB Transmission: 

28 Techniques to Decrease TB Transmission Instruct patient to: Cover mouth when coughing or sneezing Wear mask as instructed Open windows to assure proper ventilation Do not go to work or school until instructed by physician Avoid public places Limit visitors Maintain home or hospital isolation as ordered

PowerPoint Presentation: 

29 Evaluation for TB Medical history Physical examination Mantoux tuberculin skin test Chest x-ray Bacteriologic exam (smear and culture)

Symptoms of TB: 

30 Symptoms of TB Productive prolonged cough * Chest pain * Hemoptysis * Fever and chills Night sweats Fatigue Loss of appetite Weight loss *Commonly seen in cases of pulmonary TB

Chest x-Ray: 

31 Chest x-Ray Obtain chest x-ray for patients with positive TST results or with symptoms suggestive of TB Abnormal chest x-ray, by itself, cannot confirm the diagnosis of TB but can be used in conjunction with other diagnostic indicators

Sputum Collection: 

32 Sputum Collection Sputum specimens are essential to confirm TB Specimens should be from lung secretions, not saliva Collect 3 specimens on 3 different days Spontaneous morning sputum more desirable than induced specimens Collect sputum before treatment is initiated

Smear Examination: 

33 Smear Examination Strongly consider TB in patients with smears containing acid-fast bacilli (AFB) Use subsequent smear examinations to assess patient’s infectiousness and response to treatment

Culture: 

34 Culture Used to confirm diagnosis of TB Culture all specimens, even if smear is negative Initial drug isolate should be used to determine drug susceptibility

Treatment of Latent TB Infection: 

35 Treatment of Latent TB Infection Daily Isoniazid therapy for 9 months Monitor patients for signs and symptoms of hepatitis and peripheral neuropathy Alternate regimen – Rifampin for 4 months

Treatment of TB Disease: 

36 Treatment of TB Disease Include four 1 st -line drugs in initial regimen Isoniazid (INH) Rifampin (RIF) Pyrazinamide (PZA) Ethambutol (EMB) Adjust regimen when drug susceptibility results become available or if patient has difficulty with any of the medications Never add a single drug to a failing regimen Promote adherence and ensure treatment completion

Directly Observed Therapy (DOT): 

37 Directly Observed Therapy (DOT) Health care worker watches patient swallow each dose of medication DOT is the best way to ensure adherence Should be used with all intermittent regimens Reduces relapse of TB disease and acquired drug resistance

Clinical Monitoring: 

38 Clinical Monitoring Instruct patients taking TB medications to immediately report the following: Rash Nausea, loss of appetite, vomiting, abdominal pain Persistently dark urine Fatigue or weakness Persistent numbness in hands or feet

Drug Resistance: 

39 Drug Resistance Primary - infection with a strain of M. tuberculosis that is already resistant to one or more drugs Acquired - infection with a strain of M. tuberculosis that becomes drug resistant due to inappropriate or inadequate treatment

Barriers to Adherence: 

40 Barriers to Adherence Stigma Extensive duration of treatment Adverse reactions to medications Concerns of toxicity Lack of knowledge about TB and its treatment

Improving Adherence: 

41 Improving Adherence Adherence is the responsibility of the provider, not the patient and can be ensured by: Patient education Directly observed therapy (DOT) Case management Incentives/enablers

Measures to Promote Adherence: 

42 Measures to Promote Adherence Develop an individualized treatment plan for each patient Provide culturally and linguistically appropriate care to patient Educate patient about TB, medication dosage, and possible adverse reactions Use incentives and enablers to address barriers Facilitate access to health and social services

Completion of Therapy: 

43 Completion of Therapy Based on total number of doses administered, not duration of treatment Extend or re-start if there were frequent or prolonged interruptions

Meeting the Challenge: 

44 Meeting the Challenge Prevent TB by assessing risk factors If risk is present, perform TST If TST is positive, rule out active disease If active disease is ruled out, initiate treatment for LTBI If treatment is initiated, ensure completion

Remember: 

45 Remember “A decision to test is a decision to treat.”