TB Flashcards
Objectives
1
Q
Tuberculosis (TB) Infection
A
disease caused by mycobacterium tuberculosis
2
Q
TB incidence / risk factors
A
- 1/3 population latently infected
- reactivation is cause of most active cases
3
Q
TB etiology/infectious
A
- transmission person to person via small droplets
- Long time period btwn initial infection and overt dz symptoms as a granulomatous response
- Primary a pulmonary dz but you can get extrapulmonary TB too
4
Q
TB agent/basic pathophysiology
A
- mycobacterium: small, rod shaped, aerobic, non-spore forming bacilli
- cell walls have high concentration of lipids/waxes
- AFB- use Ziel Neelsen stain
- Transmitted via aerosolized droplets (can remain in air for hours)
- Bacilli need to reach alveoli to be infectious – you will have numerous bacilli in cavitary lesions
- Alveolar macrophages engulf bacilli, replicate inside, spread via blood
- A lto of time the host will be able to fight off the bacteria but it travels and makes homes throughout the body as granulomas develop
- At risk pts: infancy under 4, sick elderly, immunocompromised ** (aids, transplants, chemo), people who live or work in crowded areas (homeless shelters, nursing homes, prisons), alcoholism
5
Q
TB clinical presentation (signs and symptoms)
A
- Atypical
* Fever, nonproductive cough
* Unilateral lower lobe patchy infiltrates or hilar adenopathy
- Atypical
- Pleurisy- stabbing lung pain
* Effusion, sometimes without focal infiltrate
* PPD strongly positive
* Fever, cough, pleuritic chest pain, dyspnea
* Pleural biopsy, thoracentesis
- Pleurisy- stabbing lung pain
- Direct progression from primary TB to upper lobe involvement
- Systemic Dissemination
* Children
* HIV Patients
- Systemic Dissemination
6
Q
TB dx evaluation
A
- try to refrain/be safe when doing bronchoscopy/cough producing procedures due to spread
- DX:
- CXR for
- Upper lobe fibronodular then fluffy in apices
- The lesions coalesce, then cavitate, then have central necrosis
- Lower lobe disease is seen in less than 15% of HIV negative adults
- May have normal CXR
- Hilar lymphadenopathy common
- Sputum culture- ALWAYS do to get sensitives and check for resistance (can use saline if needed)
- GOLD STANDARD IS CULTURES ~~ 3-6 wks long
- AFB with radiologic and clinical correlation to make dx highly TB- 3 AFBs needed (1 every day for 3)
- Need 3 negatives to be negative
7
Q
TB management plan
A
- prevention:
- medication via Directly observed therapy (someone has to watch you take meds)
- Isolation
- Surgical mask
- Negative pressure room- HEPA filter
- UV Germicidal Irradiation
8
Q
TB complications
A
- Hemoptysis
- Massive hemoptysis rare
- Spontaneous Pneumothorax
- Less common
- Bronchiectasis
- Extensive pulmonary destruction
- Venous Thromboembolism
- Hypercoaguable state
- Increased risk of malignancy
- Chronic pulmonary aspergillosis
9
Q
granuloma
A
mass of granulation tissue, typically produced in response to inflammation, infection or presence of foreign substance
10
Q
granulomatous
A
immunodeficiency disease that inc body’s susceptibility to infections..
11
Q
Primary TB
A
initial infection which rarely causes significant symptoms (dormancy)
12
Q
active pulmonary infection
A
- constitutional symptoms paired with history for risk factors
- fever, night sweats, wt loss*, malaise, fatigue, CP, dyspnea
- LRTI symptoms: cough/hemoptysis
- Or fever alone for weeks
- Duration: longer than 3 weeks
- This can be reactivation dz
- Reactivation: shows as apical posterior segments involved on CXR
- Dx: PPD/TST, sputum sample and TB culture then IGRAs
13
Q
latent pulmonary TB
A
- >=10 with medical conditions which make the patient at high risk (anti-TNF agents for RA, etc.)
- Younger than 35 and at high risk with >=10mm
- Foreign born from a high prevalence country
- Medically underserved, low income populations, black, Hispanic and native Americans
- Prison, nursing home and mental institution residents
14
Q
extra-pulmonary TB
A
- bacilli are more rare with this
- pleural effusions show exudate with low glucose, high lymphocytes, but rarely has positive AFB
- Can be hypersensitivity rxn or direct spread
- After lungs, you find it MC in Lymph nodes (posterior cervical and supraclavicular)
- Can cause:
- In Gu, pyuria, endometriosis, blood in urine
- In bones, TB can be in your vertebral column called Pott’s Disease
- In GI: find in terminal ileum/cecum
- In CNS: subacute, basilar or hydrocephalus ; tx w/steroids
- In heat: pericarditis
15
Q
Military TB
A
- widespread dissemination with tiny lesions …. “millet seeds”
- Common in: lungs, liver, spleen, bones, joints
- Can be primary or reactivation
- Can present as acute or subacute
- Same tx as pulmonary TB but longer
16
Q
TB DDx
A
- Community acquired pneumonia
- MAI
- Lung abscess (staph aureus, strep. Pneumoniae)
- Lung cancer
- Sarcoidosis
- Wegner’s granulomatosis
17
Q
PPD test
A
PPD= Purified Protein Derivative = TST = Tuberculin skin test
- Delayed hypersensitivity reaction that is associated with development of TB rxn
- You measure INDURATION after 48-96 hours of intradermal injection of protein antigens
- Skin test reactivity occurs 4-6 wks after infection
- 20% of adults with active TB do not respond to PPD— false-positive in those with BCG vaccine or negative in immunocompromised pts
18
Q
Who gets PPD?
A
- Over 65
- reactivation risk
- mmunocompromised
- nursing home pts
- yearly healthcare workers
19
Q
How is PPD delivered?
A
- 0.1 mL injected intradermally; no band aid applied
- Read 48-72 hrs later
- Measure induration (palpable, raised area) NOT erythema
20
Q
Define “positive” PPD in light of the patient population being tested
A
- 5 mm- positive in pts w/ : HIV, recent TB contacts, nodular/fibrotic changes on CXR, organ/chemo pts
- 10 mm- positive in pts w/: recent immigration (5 yrs), IVDA, high risk employees (prison/hospitals/homeless), lab personnel, comorbids, children < or high risk adults
- 15 mm: ppl w/o risk factors
21
Q
Discuss the role of interferon gamma release assay (IGRA) testing in screening and diagnosis of TB
A
- Positive PPD would raise concern for latent infection at least
- CXR is indicated at this point
- Tx depends on pt history
- Important false poistives: BCG and nontuberculous mycobacterium (MAC)
- IGRA’s- interferon gamma release assay = Quantiferon-GOLD or T SPOT.m… $$$$$
- Blood test but it cannot differ between latent or active dz
- Antigens derived from TB mix with pt’s WBC which release interferon gamma – 24 hours for results
22
Q
latent pulmonary/ active pulmonary TB tx
A
- Admit if: hypoxic or dyspneic
- All staff need N95 and droplet isolation protocol
- Negative pressure room
- Standard in US: DOT (direct observed therapy)
- Multidrug tx to prevent resistance… don’t give monotherapy
- RIPE for 6 months
- R: Rifampin
- I: Isoniazid w/ vitamin B6
- P: Pyrazinamdie- for 1st 2 months
- E: Ethambutol – for 1st 2 months
- AE:
- Hepatotoxicity (RIF, INH, PZA) – need LFTs and hepatitis panel
- EMB: visual acuity baseline testing needed (ocular toxicity)
- All can cause rash- stop all drugs at one and resume one at time
- Drug Fever: same as rash
- RIPE for 6 months
- For active TB: you need sputum cultures at 2 months to show its working
- If positive, treat for 9 months
- Latent TB: 9 months of isoniazid is preferred due to bactericidal
- Or 4m onths of RIF
- Do not give RIF aloen to HIV pts due to resistance potential
- Who to treat for latent?
- HIV with >=5mm
- Close contacts of newly diagnosed infectious tb >=5, and children under 4 who have been exposed
- Recent converters – whose never been positive b4 but 10 yrs later gets positive PPD
- People with >=5mm and abnormal CXR indicating old infection (fibrotic changes)
- IV drug users >=10mm
- >=10 with medical conditions which make the patient at high risk (anti-TNF agents for RA, etc.)
- Younger than 35 and at high risk with >=10mm
- Foreign born, medically underserved, prison, nursing home, mental institution
23
Q
the role of Bacillus Calmette Guerin (BCG) vaccination in other countries and how it may affect PPD interpretation
A
Those who get a BCG will ALWAYS have a positive PPD indicating a false positive. It is not worth it to get a PPD on these patients. It is administered in other countries due to the high prevalence of TB to prevent childhood TB and military TB. Not recommended in US.
- You can do a TSPOT on pts with BCG- will not produce false positive
24
Q
A
