ID Flashcards
what bacteria cause the most TB in the US? what are 4 other bacteria that can cause it?
mycobacterium tuberculosis
mycobacterium bovis
mycobacterium africanum
mycobacterium microti
mycobacterium canetti
what are the two populations of people that TB can be divided by?
hight risk for becoming INFECTED with TB
high risk for DEVELOPING TB DISEASE
what are 7 things that can put someone at high risk for TB INFECTION (not disease)
- close contact
- foreign born
- low income and homeless
- health care workers in high risk groups
- racial and ethnic minorities
- infants, children and adolescents
- IV drug users
name five areas of the world where TB is common?
- asia
- africa
- russia
- eastern europe
- latin america
what groups of people are at risk for developing TB disease!? (7)
- people with HIV (thats why prevalence increased in the 80s)
- infection of TB within last two years (5% risk, and 10% lifetime)
- infants and children
4. prolonged therapy with corticosteroids
- IV drug use
- diabetes
- silicosis
what is the greatest risk factor for devloping TB?
HIV!!! 7-10% risk for devloping TB disease each year when infected with both TB and HIV
are people with LTBI infectious? what percent of these people will go on to develope the disease?
no they aren’t infectious!!
10% will go on to develope disease!
Explain the pathogenisis steps for TB (5 steps)
- tubercle bacilli are inhaled and travel to alveoli
- multiple in alveoli, infection begins
- small number of tubercle bacilli enter bloodstream and spread throughout body
- within 2-4 weeks macrophages survive bacilli, form a barrier shell that keeps the bacilli contained and under control know as LBTI
- if the immune system can’t keep tubercle bacilli under control, they multiple rapidly and cause TB DISEASE *it can occur in other places in the body too*
Is LTBI treated with medication?
YES IT IS
you want to prevent these patients from getting it in the future!!!
who is high priority treatment for LTBI with a TST >5 mm or postitive IGRA? (5 things)
- close contacts of those with infectious TB disease
- HIV
- chest xrays indicating previous TB
- organ donor transplants
- immunocomprimised patients
who is high priority for LTBI treatment >10 mm or positive IGRA test? (5 things)
- people who came to US within last 5 years where TB is common
- IV drug users
- live or work in high risk facilities
- micro labatories
- children
what are the two ways HIV can influence the path of TB?
- person with LTBI becomes infected with HIV and then developes TB disease as the immune system is weakened
- a person with HIV becomes infected with TB and rapidly developes the disease
multi-drug resistant TB is resistant to which drugs?
isoniazid and rifampin (2 first line drugs avaliable)
extensively drug resistant (XDR-TB), what drugs are they resistant to?
isoniazid and rifampin, PLUS fluoroquinolones and at least 1 of the 3 second line drugs
**this is a major issue around the world**
how long should a patient be treated for TB?
what if this person has pos sputum after 2 months of treatment?
at least 6 months
if cavities on chest xray and postitive sputum cultures at 2 motnhs then treatment should be extended for 9 months
what are the three phases of TB infection treatment?
1.initial phase: first 8 weeks of treatment, four drugs are used
isoniazid, rifampin, pyrazinamide, ethambutol
2. continuation phase: after first 8 weeks of treatment, bacilli remaining after initial phase are treated with at least two drugs
3. relapse phase: occurs when treatment is not continued for long enough, surviving bacilli may cause TB disease at a later time
in order to prevent drug resistance, TB disease must be treated with at least how many drugs?
2 ones the organism is suseptible to
Tuberculosis
what are the classic symptoms assosicated with TB (clinical and xray)?
clinical symptoms:
coughing >3 weeks
pleuritic chest pain
hemoptysis
positive rales
infiltrates (collection of fluid and cells in lung tissues)
cavities (hollow spaces within lung usually in the upper lobe)
caseating granuloms on biopsy (necrotizing granulomas)
what tests do you use to diagnose TB?
- tuberculin skin test (TST)
2. interferon gamma assays (IGRAS)-measures immune response to m. tuberculosis, less likely to be incorrect compared to TST
3. culture with AFB staining
-need 3 specimens, 8-24 hour collection intervals, can induce with inhaling saline mist spray
4. chest x-ray (infiltrates and cavities)
5. nucleic acid amplification test
6. bronchoscopy or gastric wash if having hard time getting sample
explain the tuberculin skin test? what can’t this test do? what are positive test results for the three groups of people?
in lastent infection positive 2-4 weeks after infection
-injected with inactive tubercle bacilli, read within 48-72 hours
**this test can’t differentiate between latent and active TB, just that a person has been infected at some point**
Positive test results:
15 mm in normal patients
10 mm in immigrants, children
5 mm in HIV, immunsuppressed, positive chest xray, primary TB exposure
explain the difference on chest xray between primary and reactivated TB?
primary: homogeous infiltrates, hilar/paratracheal lymph node englargement, middle/lower lobe consolidation
reactivation: fibrocavity apical disease, nodules, infiltrates **TB reactivation presents at the top of the lungs instead of wher eit happened originally**
what is the gold standard for TB testing?
acid fast bacilli tests
3 negative tests are considered negative!!
how long should a person be isolated and on treatment before being allowed in public when they have TB?
need to be isolated for a minimum of 2 weeks
what are the four drugs you use during the initial treatment phase for TB? what are their side effects? how do you treat someone if they have been exposed to someone with active TB? what is the treatment regiment for LBTI?
“RIPE acronym
- rifampin (hepatitis, flu, orange body secretions)
- isoniazid (hepatitis, periphreal neuropathy, give B6 to prevent risk)
- Pyrazinamide
- ethambutol (optic neuritis)
**for LBTI: treat with isoniazid and pyrazinamide for 9 months, or 12 months if HIV pos or granulomas present on CXR**
**if someone is exposed to patient with active TB, then treat them emipircally for 12 weeks until negative TB can be obtained**
In TB, explain the differences between LTBI and TB disease in these characteristic:
- active/inactive bacilli
- chest xray findings
- sputum smears
- symptoms
- infectivity
- a case of TB or not
what should you connect Ghon complexes and Ranke complexes? what are they?
TB
ghon complexes: calcified primary focus
ranke complexes: calcified primary focus and hilar lymph nodes
**these represent healed primary infection**
**what is the highest risk group for HIV infection***
men having sex with men