TB and MAC- Exam 2 Flashcards
What organism causes most TB disease in the U.S.?
Mycobacterium Tuberculosis
How is TB spread?
Respiratory droplets
The probability that TB will be transmitted depends on what four factors?
Infectiousness of the TB patient, Environment, Frequency and duration of the exposure, and Immune status of the individual
What is Latent TB Infection (LTBI)?
It is TB that has remained dormant and then appears at times of immunocompromise. Non-infectious and asymptomatic.
When a person inhales air that contains droplet nuclei containing M. tuberculosis, where do the droplet nuclei go and where does infection begin?
After inhalation, the bacteria travels to the alveoli where it multiplies in the lungs then can spread through the bloodstream.
In people with LTBI how does the immune system keep the tubercle bacilli under control? What happens if the immune system fails and the bacilli begin to multiply rapidly?
Macrophages surround the tubercle bacilli and LTBI occurs but if the immune system fails then replication can no longer be kept under control and active TB infection will take place.
List at least 4 differences between LTBI and TB.
Latent TB is controlled by the immune system, non-infectious, asymptomatic, chest x-ray normal.
TB is active and is not controlled by the immune system, infectious, symptomatic, chest x-ray abnormal.
What percentage of those with LTBI will develop TB (non-HIV infected)?
10%
Name at least two conditions that appear to increase the risk that LTBI will progress to TB disease?
Those taking immunosuppressive therapy and those who have HIV.
TB primarily affects the lungs. Name two other sites that “extrapulmonary” TB can occur?
It can occur in the spine and brain.
. Name 7 groups of people who are more likely to be exposed or infected with TB
Medically underserved, People in Correctional facilities, People in Nursing homes, People in Homeless Shelters, Health care workers, People who visit areas with high prevalence of TB disease, People who abuse drugs or alcohol
Name at least 2 ethnic groups that are disproportionately affected by TB?
Asian and Hispanic/Latino Descent
Give 2 possible reasons why these ethnic groups may have a higher rate of TB
Lower Socioeconomic status and higher incidence of HIV infection (TB is prevalent with AIDS)
When a child has TB infection or disease, what does it tell us about the spread of TB in the child’s home or community? Name 3 things:
TB was transmitted relatively recently
Person who transmitted the TB to the child may still be infectious
Others may have also been exposed
Name 5 groups of people who are more likely to develop active TB disease once infected:
Children younger than 5 years of age, People receiving immunosuppressive therapy, People who have a low body weight, People who smoke cigarettes or abuse drugs/alcohol, People who have been infected with M. tuberculosis within the past 2 years
If a person is infected with both M. tuberculosis and HIV, what are his or her chances of developing TB disease? How does this compare to the risk for people who are infected only with M. tuberculosis?
7% to 10% each year. The risk for developing TB is much higher when the patient also has HIV with infection than just the infection of M. tuberculosis alone. Those who are infected with Mycobacterium Tuberculosis have a 5% chance of developing TB.
What diagnostic test is used to screen for and diagnose latent TB (LTBI)?
Mantoux tuberculin skin test or a blood test (interferon-gamma release assay) and if either is positive then need a chest x-ray
With the TST, after the injection is administered, when is the patient’s arm examined?
48 to 72 hours
What 2 factors determine the interpretation of a skin test reaction as positive or negative?
Induration size and patient risk factors.
For which groups of people is > 5 mm of induration considered a positive reaction? Name 4.
Patients with HIV infection or risk for HIV, recent close contact to someone with TB, patients with CXR consistent with prior TB, patients with organ transplants or other immunocompromised patients
For which groups of people is > 10 mm of induration considered a positive reaction? Name 7.
-Countries with high rate of TB
- low body weigt
- less than 5 years old
- high risk setting
- teenagers exposed to active TB
- IV drug user
- Mycobateriology lab worker
For which group of people is > 15 mm of induration considered a positive reaction?
Everyone else
Name 3 factors that can cause a false positive reaction to the TST?
-Previous BCG vaccine for TB
-Infection with non TB mycobacteria
-Incorrect measurement
-Incorrect antigen
Name 6 factors that can cause a false negative reaction to the TST
Recent TB infection within 8-10 weeks
Anergy so absence of normal immune response or weakened immune system
Age <6 months old
Recent live virus vaccine such as MMR
Incorrect administration
Incorrect interpretation
After TB has been transmitted to someone, how long does it take before TB infection can be detected by the TST?
Approximately 8 to 10 weeks
True or False: If a patient has a negative TST result, but has symptoms of TB disease, they should be medically evaluated for active TB disease
True
What are the 5 components for conducting a medical evaluation for diagnosing TB disease?
- Medical History evaluation
- Physical exam
- TB testing
- Chest x-ray
- Bacteriological examination (including culture)
NEED TO BE COMPLETED IN THIS ORDER
What are the general symptoms of TB disease?
Fever, chills, night sweat, fatigue, weight loss, anorexia
What are the pulmonary symptoms of TB disease?
Cough lasting for more than 3 weeks, chest pain, some rales may be present, hemoptysis
True or False: A chest x-ray can confirm that a person has TB disease.
False, a positive chest x-ray alone cannot confirm TB diagnosis, would then need to culture to confirm.
CXR more useful in ruling out pulmonary TB in asymptomatic patients who are testing positive
LTBI patients can also have normal chest x-ray findings
How do you confirm the diagnosis of TB disease?
Only bacterial culturing can confirm active TB, but it takes up to 6 weeks.
NAA test and AFB smear do not confirm diagnosis, but if both are positive, the patient is presumed to be infected and should be treated.
True or False: Target testing should be performed routinely on ALL individuals.
False, routine testing should only take place in individuals in high-risk groups (like immunocompromised, pts with HIV, transplant patients, cancer patients, etc)
What is the preferred treatment regimen for LTBI?
Isoniazid daily for 9 months
Why do we treat LTBI?
We do not want the disease to progress to Active TB, most risk of developing TB from LTBI in the first 2 years.
Treating LTBI can also rule out active TB infection, determine if the patient has been treated for TB, or if there are other complicating factors.
What LTBI treatment regimen may be recommended for people with a positive IGRA or a TST result who have been exposed to INH-resistant TB?
Rifampin given daily for 4 months
True or False: All persons who have been close contacts to someone with active TB should be treated with an LTBI regimen even if they have a negative TST or IGRA result.
False, they need to be retested in 8 to 10 weeks.
If a close contact has a negative initial TST or IGRA, when should they be retested?
8 to 10 weeks
True or False: A 4 year old child who tested with an initial negative TST result who has been in close contact with someone with active TB should be treated with an LTBI regimen.
True, because the child is under 5 and they have a high risk for developing TB. They can be re-tested in 8-10 weeks to determine if they should continue or discontinue treatment.
Why is it important to exclude the possibility of TB disease before giving a patient LTBI treatment?
Because it can lead to drug resistance.
Also, active TB needs all four treatments in the first 8 weeks of treatment (rifampin, isoniazid, pyrazinamide, ethambutol) and LTBI treatment is just rifampin or isoniazid.
What is the definition of multidrug-resistant TB (MDR TB)?
Resistant to at least isoniazid and rifampin which are the two drugs for first-line TB treatment.
Which 4 drugs are recommended for the initial treatment of TB disease?
Rifampin
Isoniazid + Vitamin B6 to decrease peripheral neuropathy
Pyrazinamide
Ethambutol
Name the drug or drugs that may cause each of the following symptoms or adverse reactions. peripheral neuropathy:
isoniazid
Name the drug or drugs that may cause each of the following symptoms or adverse reactions. Hepatitis:
Pyrazinamide, Isoniazid, Rifampin
Name the drug or drugs that may cause each of the following symptoms or adverse reactions. Eye damage:
Ethambutol
Name the drug or drugs that may cause each of the following symptoms or adverse reactions. Orange colored urine____
rifampin
Name the drug or drugs that may cause each of the following symptoms or adverse reactions. Multiple drug interactions, including reaction with antiretroviral drugs
Rifampin
How can clinicians determine whether a patient is responding to treatment?
Check for TB symptoms (clinical) because should start improving in 2 months, Conduct bacteriology exam of sputum or other specimens, check CXR
True or False: TST or IGRA can be used to determine if a patient is responding to treatment.
False, TST or IGRA cannot be used to determine if a patient is responding to treatment.
Name one criteria that counts as verified TB and should therefore be reported
If the patient has a positive NAA test for M. tuberculosis accompanied by culture for mycobacteria species.
True or False: Persons with LTBI are infectious.
False, they are not infectious.
What are the NTM infections?
Mycobacterium avium complex
Mycobacterium abscessus
Mycobacterium kansasii
____ is the MC cause of NTM pulmonary disease in the US
Mycobacterium Avium Complex (MAC)
How is MAC generally acquired?
inhaled through water spores
NOT human to human or human to animal transmission
How does the process of MAC work?
When macrophages try to attack, MAC bacteria will infect the macrophages, as they are resistant to lysozyme activity → leads to inflammation
More macrophages try to surround the infection, granulomas form and eventually lead to nodular bronchiectasis → bronchi become scarred/damaged and struggle to clear mucus from the lungs
If this is not treated or progresses, we see fibrocavitary disease where bacteria infect more lung tissue → like in TB
Infection can move into the lymphatics then bloodstream and disseminated disease can progress from here in immunocompromised individual
T/F: MAC is easier to eradicate than TB
FALSE! TB is easier to eradicate than MAC
Productive cough
Weight loss, lethargy
Fever, night sweats
+/- cervical lymphadenitis
What am I?
pulmonary MAC
Fever
Weight loss, fatigue
SOB, cough
Abdominal pain, diarrhea, anorexia
What am I?
What is the common pt population?
Disseminated MAC
immunocompromised pts think AIDS
What is the dx work up for MAC include?
Need to exclude TB first
CXR/Chest CT
AFB: acid fast and cultures (sputum/blood if you suspect disseminated TB)
What is the treatment for MAC? For how long? What is severe or cavitary lesions are present?
macrolides (azithromycin or clarithromycin)
ethambutol
Rifamycin (rifampin/rifabutin)
amikacin or streptomycin can be added
12 months: often difficult to eradicate the first time
What do you give a MAC pt if they are unable to take macrolides?
aminoglycosides or fluoroquinolones
What do you do if a MAC patient failed medical therapy?
lung resection may be considered and is generally effective with low rates of morbidity
saline inhalation and chest wall oscillation (percussion) vests may be helpful - especially for those who have concurrent chronic pulmonary diseases
What is the emerging antipsychotic treatment for MAC?
thioridazine
_____ presents the same as MAC but is more commonly found in tap water in cities
M. kanasii
_____ presents the same as MAC but more commonly affects patients with underlying lung diseases
M. abscessus
