Tuberculosis Flashcards
What organism causes tuberculosis?
Mycobacterium tuberculosis (vast majority in U.S.)
M. tuberculosis organisms are also called tubercle bacilli
Other myobacteria that can cause tuberculous disease include: M. bovis M. africanum M. microti M. Canetti
What is a common type of Mycobacteria that does not cause TB?
M. avium
Mycobacteria that do not cause TB are often called nontuberculous mycobacteria. Nontuberculous mycobacteria are NOT usually spread from person to person
Where does TB disease usually occur?
in the lungs (pulmonary TB), but can also occur in other places in the body (extrapulmonary TB)
What is disseminated TB
When tubercle bacilli enter the bloodstream and are carried to all parts of the body, where they grow and cause disease in multiple sites
LTBI
Latent TB Infection:
When someone is infected with TB and their immune system keeps the bacilli under control, it is referred to as LTBI. People with LTBI do not have symptoms of TB, and they cannot spread TB to others
TB Disease
In some people with LTBI, the immune system cannot keep the tubercle bacilli under control and the bacilli begin to multiply rapidly, resulting in TB disease (AKA Active Disease). People with TB disease can spread TB to others
When can TB Disease occur?
Very soon after infection or many years after infection
Risk factors for LTBI
About 10% of people with LTBI will develop TB disease at some point, but the greatest risk is in the first year or two after infection. Certain medical conditions also put some people at higher risk
Risk factors for people infected with both M. Tuberculosis and HIV
With people infected with both, risk of developing TB disease is about 7 to 10 % per year.
For people only infected with M. tuberculosis, the risk of developing TB disease is 10% over a lifetime
State of Bacilli - LTBI vs TB Disease (pulmonary)
LTBI - inactive tubercle bacilli in the body
TB Disease - Active tubercle bacilli in the body
Test Results - LTBI vs TB Disease (pulmonary)
Tuberculin skin tests or interferon-gamma release assay tests results usually positive for both
Chest X-ray results - LTBI vs TB Disease (pulmonary)
LTBI - Chest x-ray usually normal
TB Disease - Chest x-ray usually abnormal
Sputum Smears and Cultures Results - - LTBI vs TB Disease (pulmonary)
LTBI - Sputum smears and cultures negative
TB Disease - Sputum smears and cultures may be positive
Symptoms - LTBI vs TB Disease (pulmonary)
LTBI - No symptoms
TB Disease - Symptoms such as cough, fever, weight loss
Infectiousness - LTBI vs TB Disease (pulmonary)
LTBI - Not infectious
TB Disease - Often infectious before treatment
Diagnosis - LTBI vs TB Disease (pulmonary)
LTBI - Not a case of TB
TB Disease - A case of TB
Symptoms of TB Disease
Most people will have symptoms:
TB (Pulmonary)
- Cough lasting 3 weeks or more
- Pain in the chest when breathing or coughing
- Coughing up sputum or blood
General symptoms of TB disease (pulmonary or extrapulmonary):
- Weight Loss
- Loss of appetite
- Fatigue
- Malaise
- Fever
- Night Sweats
Other symptoms depend on the part of the body that is affected by the disease.
Drug-resistant TB
Drug-resistant TB is caused by M. tuberculosis organisms that are resistant to at least one of the first line TB treatment drugs
What are the first-line TB treatment drugs
- isoniazid
- rifampin
- pyrazinamide
- ethambutol
Primary resistance
When drug-resistant TB can be transmitted person to person
Secondary resistance
Develops during TB treatment, either because patient was not treated with appropriate regimen or patient did not follow the treatment regimen as prescribed.
What are the two best first line TB treatment drugs
- isoniazid
- rifampin
XDR TB
Extensively drug-resistant TB
Occurs if the tubercle bacilli are resistant to isoniazid and rifampin, plus resistant to any fluoroquinolone (e.g. levofloxacin and moxifloxacin) and at least one of three injectable second-line drugs (e.g. amikacin, kanamycin, or capreomycin).
What are the three injectable second line drugs for TB
- amikacin
- kanamycin
- capreomycin
MDR TB
Multidrug-resistant TB
If tubercle bacilli are resistant to at least isoniazid and rifampin
Poly-resistant TB
Resistant to at least two TB drugs, but not both isoniazid and rifampin
Mono-resistant TB
Only resistant to one drug
How is TB spread?
TB is spread from person to person through the air. Tiny particles containing M. tuberculosis may be expelled into the air (droplet nuclei)
How long can TB droplet nuclei stay in the air?
Droplet nuclei can remain suspended in the air for several hours, depending on the environment. Inhaling air that contains these droplets can lead to transmission
What affects whether TB will be transmitted after being exposed to an infected person
- Infectiousness of person with TB Disease
- Environment in which exposure occurred
- Length of exposure
- Susceptibility (immune status) of the exposed individual
What affects the infectiousness of a TB patient?
The infectiousness is directly related to the number of tubercle bacilli that the patient expels into the air.
- Presence of a cough
- Cavity in the lung
- Positive sputum smear result and / or culture
- Site of TB disease in lungs, airway, or larynx
- Not covering mouth and nose when coughing
- No or inadequate treatment
- Cough inducing procedures
What people are at highest risk for contracting TB?
Those who spend a lot of time in enclosed spaces with people who have TB disease (family, friends, roommates, coworkers)
What are the most infectious places for TB?
Health care settings (clinics, hospitals, home-based health care)
Congregate settings (nursing homes, correctional facilities, homeless shelters),
Drug treatment centers
What people are at high risk for exposure to TB?
- Contacts of people known or suspected to have TB
- People who have come to the United States from areas of the world where TB is common
- People who work in high risk settings
- High-risk racial or ethnic minority populations
- Infants, children, and adolescents exposed to adults in high risk groups
What are some areas of the world where TB is common?
- Asia
- Africa
- Russia
- Eastern Europe
- Latin America
What people are at high risk for developing TB disease once infected with M. Tuberculosis?
- People living with HIV
- Recently infected with M. tuberculosis (within the past 2 years)
- Medical conditions known to increase the risk for TB
- Cigarette smokers and persons who abuse alcohol or drugs
- Children younger than 5 years
What medical conditions are known to increase the risk for TB once infected with M. tuberculosis?
- Silicosis
- Diabetes Mellitus
- Severe Kidney Disease
- Certain types of cancer
- Certain intestinal conditions
- Organ transplant recipients
- Immunosuppressive therapy
- Low body weight
What are the current methods for detecting M. tuberculosis infection?
- Interferon-gamma release assays (IGRAs), which are blood tests, such as the:
- – QuantiFERON-TB Gold Plus (QFT-Plus)
- – T-Spot TB Test (T-Spot)
- Mantoux tuberculin skin test (TST)
The IGRAs and TST measure different components of the immune response and are administered differently
TST
Mantoux Tuberculin Skin Test
The TST test is done by using a needle and syringe to inject tuberculin between the layers of the skin, usually on the forearm. After 48 to 72 hours, the patient’s arm is examined for a reaction (an induration). The diameter of the indurated area (the swelling, not the redness) is measured across the forearm.
Most people with TB infection have a positive reaction to tuberculin. The interpretation of the TST depends on the size of the induration, and the person’s risk factors for TB
What factors of a TST may cause false positives?
- Infection with non-tuberculosis mycobacteria (NTM)
- Vaccination with BCG (bacille Calmette-Garin, a vaccine for TB disease)
- incorrect methods
What factors of a TST may cause false negatives
- Anergy (a lack of reaction by the body’s defense mechanisms to foreign substances)
- Recent infection
- Very young age
- Recent live virus vaccination
- incorrect methods
What induration is considered positive for a TST?
5 or more millimeters for people with:
- HIV
- Recent contact to infectious TB
- People who have previously had TB
- Patients with organ gtransplants and other immunosuppressed patients
10 or more millimeters for people:
- Who came to the US from areas where TB is common
- Persons who abuse drug or alcohol
- Mycobacteriology lab workers
- Those in high risk congregate settings
- With high risk medical conditions
- Children younger than 5
- Children and adolescents exposed to adults in high risk categories
IGRAs
Interferon-Gamma Release Assays
Blood tests for TB infection that measure a person’s immune reactivity to M. tuberculosis
- Results can be available within 24 hours, but blood samples must be processed within 8-32 hours
- Prior BCG vaccination does not cause a false-positive IGRA test result
Followup TB testing
Patients with positive results (any test) should be evaluated for TB disease. If ruled out, should be considered for LTBI treatment.
Recent contacts who have tested negative (either test) should be retested 8 to 10 weeks after the last time they were in contact with a person who has TB.
What are the 5 components for conducting a complete medical evaluation for diagnosing TB disease?
- Medical history
- Physical examination
- Test for TB infection
- Chest X-ray
- Bacteriologic examination
How is drug resistance prevented in TB
By using multiple drugs. Using only one drug to treat TB disease can create a population of tubercle bacilli that is resistant to that drug
CDrug resistance can also develop when patients do not take treatment as prescribed
The form of tuberculosis that is characterized by inactive bacilli, normal chest x-ray, and negative cultures
a. passive TB inoculation
b. Latent TB infection
C. TB disease
b. Latent TB infection
Particles that spread TB from person to person through the air
a. Micro droplets
b. Boogers
c. Droplet Nuclei
c. Droplet nuclei
A strategy to identify persons who are at high risk of developing TB disease
a. isolation testing
b. contact testing
c. targeted testing
c. Targeted testing
The minimum length of time that TB disease must be treated
a. 6 months
b. 1 year
c. 2 years
a. 6 months
These are symptoms of TB disease
a. pain in the chest, coughing up blood, and pain in the chest while breathing
b. diarrhea, dizziness, and disorientation
c. coughing up blood, sudden weight gain, difficulty breathing
a. pain in the chest, coughing up blood, and pain in the chest while breathing
The infectiousness of a TB patient may be greater if these factors are present
a. Coughing, a cavity in the lung, not covering mouth and nose when coughing
b. breathing through the mouth, not dressing warmly, and undereating
c. lack of sleep, use of illegal drugs, and inadequate nutrition
a. coughing, a cavity in the lung, and not covering mouth and nose while coughing
Two methods for detecting M. tuberculosis infection
a. Mantoux tuberculin skin test and gamma wave test
b. interferon-gamma release assays and the Mantoux tuberculin skin test
c. Manray tuberculin skin test and gamma wave test
b. Interferon-gamma release assays and the Mantoux tuberculin skin test
The reason that the initial treatment regimen must include multiple drugs to which the bacilli are susceptible
a. counter-balanced medication
b. suppression of electrolytes
c. prevention of drug resistance
c. prevention of drug resistance
The term for drug-resistant TB that can be transmitted from person to person
a. microbial immunity
b. primary resisttance
c. secondary resistance
b. primary resistance
People who are most at risk of getting TB
a. Taxi drivers
b. child care providers
c. health care workers
c. health care workers
Blood tests for tuberculosis work by measure this
a. pulmonary circulation
b. immune reactivity
c. anemic tendency
b. immune reactivity
The most effective strategy to make sure patients adhere to treatment
a. compulsory medication schedule
b. directly observed therapy
c. electronic monitoring
b. directly observed therapy
Which is not true of TB?
a. Approximately 2 billion people are infected worldwide
b. There was no treatment for TB until the 1940s
c. People with TB prior to treatment were sent to sanatoriums
d. The 20% rise in TB cases seen between 1985 and 1992 was due solely to the HIV epidemic
d. The 20% rise in TB cases seen between 1985 and 1992 was due solely to the HIV epidemic
not true
How is TB transmitted?
a. Sharing food or drink
b. Person to Person through the air
c. Sharing toothbrushes
d. Kising
b. Person to person through the air
Which groups are considered more likely to be exposed to or infected with M tuberculosis?
a. Low-income groups with poor access to health care, including homeless people
b. People who live or work in high-risk residential settings
c. People who have come ot the US within the last 5 years from areas of the world whre TB is common
d. All of the above
d. All of the above
Drug resistant TB
a. Is caused by M. tubercuolosis organisms that are resistant to at least one of the first line TB treatment drugs
b. Can be transmitted from person to person or develop during TB treatment when the patient did not follow the treatment as prescribed
c. Can be mono-resistant or poly-resistant
d. All of the above
d. All of the above.
Which is not true of LTBI and TB disease?
a. people with LTBI cannot spread TB to others
b. People with LTBI often have TB symptoms
c. HIV is a risk factor for the progression LTBI to TB disease
d. About 10% of people with LTBI will develop active TB disease at some point
e. Tuberculin skin test or interferon-gamma release assay test results are usually positive for LTBI and TB disease
b. People with LTBI often have TB symptoms
What are the components of medical evaluation for TB?
a. Medical history, physical exam, tests for TB infection, chest x-ray, bacteriological exam
b. Symptom evaluation and TST
c. Physical evaluation, chest x-ray and culture
d. None of the above
a. Medical history, physical exam, tests for TB, chest x-ray, bacteriological exam
Which of the following is not true of testing for and diagnosing TB?
a. QFT-G, QFT-GIT, T-Spot all use blood samples to test for TB infection.
b. Patients with positive test results for TB infection should always be further evaluated for TB disease
c. Chest x-rays can confirm whether or not a person has TB disease
d. Culturing a specimen is necessary to confirm the diagnosis of TB disease
c. Chest xrays can confirm whether or not a person has TB disease
* Chest x-rays cannot confirm TB. However, they can rule out pulmonary TB and identify other lung abnormalities
What is the preferred treatment regimen for LTBI?
a. Rifampin daily for 4 months
b. Isoniazid twice weekly for 6 weeks
c. Nothing. No treatment is given until TB infection develops into TB disease
d. Isoniazid daily for 9 months
d. Isoniazid daily for 9 months
Which is not true of treatment for TB disease?
a. Serious adverse reactions to isoniazid include neuropathy, stomach upset, and hepatitis
b. The initial treatment of Tb disease should only include rifampin. Additional drugs are added if no response to treatment is noted.
c. Isoniazid, riframpin, pyrazinamide and ethambutol are all drug treatments for TB
d. The most effective strategy to ensure adherence to treatment is directly observe therapy (DOT).
b. The initial treatment of TB disease should only include rifampin. Additional drugs are added if no response treatment is noted.
* The regiment must include at least two drugs to which bacilli are susceptible in order to prevent drug resistance.
