Therapeutics - TB 1
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What is the organism that causes Tuberculosis?
Mycobacterium tuberculosis (other bugs need to ruled out)
What are other names that TB has been known by in history?
Consumption; Wasting disease; White plague
What proportion of the world’s population is infected with TB?
- ~ 1/3 (2 bil); worldwide - 1 person dies of TB every 15 seconds
- (active or latent disease)
What portion of the US population is infected with TB?
9-14 mil infected, with > 11,000 developing active disease in 2010
Name examples of states that have the highest rates of active TB cases in the U.S. (>3.6/100,000 population):
- Hawaii, California, Arizona, Texas, Louisiana, Florida, New York, Alaska
- Entry & settling points of entry for travelers and immigrants &/or where there are high rates of poverty/ folks with limited health care services:
- Common with Native populations as well.
What are the 3 factors contributing to a global resurgence of TB in the last few decades?
- 1) HIV/AIDS
- 2) Drug-resistance (People are not finishing therapies)
- 3) Weak health systems in many countries
What is the Typical Pulmonary presentation of Tb?
Coughs, Sneezes, Speaking, Singing – Expelling of air
How much contact dose TB usually require for transmission?
TB typically occurs in those with repeated or close, sustained contact, esp if in enclosed spaces (crowding)
Health care system patients with newly identified active disease should be controlled in what way?
Placed in respiratory isolation and be required to wear a mask if out in general areas of facility, until sputum culture shows absence of Mycobacterium
How does Infection transfer occur in TB?
Droplet nuclei to alveolar surface ( upper, posterior region) – solid caseous (necrotic) foci/nodules typically granulomas form to contain infection
In a patient with a health immune system, what form of TB would you expect?
LTBI (Latent TB infection) in those with healthy immune response
How does the Active / Reactivation form of TB progress?
Caseating (necrotizing) granulomas cavities lung destruction hypoxia, respiratory acidosis death
Under immunocompromised conditions, the ______________may open up and cause reactivation of the disease
What body system(s) may be attacked by TB?
- - the Lung is the most commonly affected body system.
- - Any part of the body can be a site of infection (including GI tract, lymph nodes, bones/joints, the brain, etc
Children and those who are immune compromised are more subject to what type of TB?
- Primary progressive pneumonia or disseminated (Miliary) TB with extra-pulmonary disease
- Can lead to rapid death
How do we differentiate between LTBI & active TB disease?
- 1) LTBI – constitutes an INFECTION with TB, but one that is being controlled by the body’s immune systems; These people are NOT symptomatic and CANNOT spread TB
- 2) Active TB disease – The infection has become active and is no longer being kept under control by the body’s immune system; Patient typically feels sick; usually has specific symptoms and can spread tuberculin bacteria with pulmonary disease.
- May be much more difficult to diagnose with atypical disease or sites of infection (atypical disease is more likely in children and immune compromised patients).
What are the Risk Factors for LTBI TB?
- Immigrant/Refugee status within the last 5 years from high risk regions
- Poor standard of living (residence or travel)
- Minority Race/Ethnicity (related to poverty)
- Low socio-economic status (crowded conditions & lack of medical care)
- Co-infection with HIV
- Frequent or continuous exposure to high risk individuals/groups – Esp infants and children
- Chemical dependency: Tobacco, Alcohol, Drugs
- Visiting endemic areas
What are the risk factors for Active TB disease?
- Age (< 5 and > 65)
- Time since infection (increased within 2 yrs post acquiring infection for developing active TB)
- HIV infection
- Immune deficiency or people on immune suppressive therapies
- Drugs and alcohol
- < 90% of ideal body weight
- Gastrectomy or a Jejuno-ileal bypass surgery (for weight loss)
- Various chronic diseases, including diabetes, chronic renal failure, leukemia, lymphoma, CA of head/neck/lungs, silicosis
About what % of people will develop ACTIVE TB disease at some time during their life after becoming infected (after developing LTBI)?
- - About 5-10% of infected people with normal immune systems
- - LTBI prophylaxis reduces the risk of active disease to about 1% (up to a 90% drop in risk)
- - Risk increased in immune compromised, and other high risk groups
Why are health care professionals generally tested with an annual TB skin test? (Consider the risk factors for active TB disease to answer this.)
- Because the risk of progression from LTBI to active TB disease is greatest within the first 2 years after initial infection, a change to Positive status on an annual PPD is of key concern for HCWs.
What are general and organ specific symptoms of active TB disease?
- *General: Fever, chills, night sweats, weight loss, appetite loss, fatigue, malaise
- *Lungs: Productive cough lasting > 3 weeks; chest pain, coughing up blood occurs later in the disease (hemoptysis) or sputum (phlegm)
- *Other Organ Systems: These will vary with the organ, and may be difficult to associate with TB
Miliary TB means what?
Term for widely disseminated disease – More common in HIV and other immune compromised patients, as well as in children.
Screening tests only assess if the patient is ___________.
Can TB tests confirm whether active TB disease is present?
What are the Skin Tests for TB?
- Tuberculin Skin Test (TST)
- Mantoux test
- PPD (Purified Protein Derivative) Test – Aplisol and Tubersol
What area is measured in a PPD test?
Area of induration (swelling), rather than of redness
What indicates a positive result for high risk patients (HIV, immune compromised; recent contact of active disease?
> or = to 5 mm induration
What indicates a positive PPD test for those with risk factors: includes health care workers, and young children, chemical dependency, immigrants?
> or = to 10 mm induration
What indicates a positive PPD for anyone?
> or = to 15 mm induration
What is the name of the Blood Assay for TB?
IGRAs (Interferon Gamma Release Assays)
Which is more specific and acurate, the skin or blood test for TB?
- IGRA (Blood) is more specific
- IGRA also does not have the false positives caused by prior BCG vaccination
IGRA bllod test for TB provides results in what time frame?
< 24 hrs
Why is the skin test for TB used more than the blood test?
Blood test is more expensive
What are the IGRA blood tests for TB named?
Quanti-FERON® – TB Gold; T-SPOT® TB
Can skin tests or blood assays differentiate between infection & active TB disease?
What are the Symptoms of TB disease?
Unexplained weight loss, night sweats, loss of appetite, fever, fatigue, cough lasting 3 or more weeks, productive cough - sputum and/or blood
Are TB PE S/S specific or non-specific?
Generally signs are nonspecific
What PE S/S are specific for TB?
- Productive cough (prolonged)
When is a chest X-ray used for TB?
Used to rule out presence of active pulmonary TB disease in a patient with a Positive PPD / IGRA
Can chest x-ray results confirm that a person has TB disease?
- A variety of illnesses may produce abnormalities whose appearance on a chest x-ray resembles TB.
What type of Sputum exam/culture would be used to evaluate for TB?
Acid-fast bacteria; culture
If _________________are found on a sputum smear, it strongly suggests TB disease (smear positive).
AFB (Acid fast bacteria)
Does a positive Acid fast bacterial smear confirm a diagnosis of TB?
- Some acid fast bacteria are not TB
Does a negative Acid fast smear exclude TB disease?
- Possible to have AFB in the smear that were not seen
What test can positively identify M. Tuberculosis?
Nucleic acid amplification (NAA) tests by amplifying DNA and RNA segments found in the patient’s specimen.
If _____________ and _____________ are both positive, patients are presumed to have TB disease and should begin treatment.
NAA test and AFB smears
What test results indicate that a patient may be infected with nontuberculous mycobacteria (NTM)?
If NAA test is negative and AFB smears are positive
What testing can confirm active disease?
Culture and Drug susceptibility testing
When testing for TB, you should also test for what other disease?
What is DOT?
- Directly Observed Therapy
- Patient meets with a health care worker every day or several times a week. The patient takes the TB medicines while the health care worker watches.
- DOT should be done at a time and place that is convenient for the patient.
The most effective strategy to ensure adherence to treatment is:
When should DOT be used for LTBI?
Using an intermittent (other than daily) regimen
When should DOT be used for Active TB?
DOT should be used for ALL patients with active TB disease, including children and adolescents. There is no way to accurately predict whether a patient will adhere to treatment without this assistance
Strategies other than DOT to promote therapy adherence, include:
- Incentives: small rewards given to the patient (gift cards or food vouchers)
- Enablers: anything that helps the patient more readily complete therapy or show up for their DOT appointment (bus tokens or cab fare)
What is the Purpose of LTBI prophylaxis?
- To prevent progression from latent TB infection to active TB disease
- LTBI “prophylaxis” reduces (but does not eliminate all) risk of progressing to active disease
- Does NOT prevent reinfection with TB
- Reduces risk among those with LTBI from about 10% to < 1% (90% reduction)
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