Pulm: Tb, Cocci, Etc. Flashcards
After initial transmission, primary tuberculosis can take ______ weeks to show as positive on PPD skin test…
6-8 weeks
In this stage of TB, macrophages ingest tubercle bacilli, creating a granuloma, rendering transmission unlikely
latent TB
Latent TB (LTBI) is present in what percent of TB cases?
95%
What percent of TB disease (active form) develops from latent TB?
5%
Patients with DM are ____ x more likely to develop TB
3x
What are 4 important lines of questioning to explore during hx in a potential TB case?
- immunocompromised?
- immigrant from high TB area?
- IVDU?
- close living quarters?
What are three major sxs of TB?
Fever, cough, CP
How long does the cough in TB persist, and what are two other features of the cough?
3+ weeks
+/- productive, hemoptysis
What might be heard on auscultation of the lungs in TB?
posttussive crackles
On PE, a patient presents with:
Dullness to percussion
decreased fremitus
This is concerning for…
TB
What 4 diagnostics are helpful in assessing TB
- TB testing (TST or IGRA)
- CXR
- Bacteriological exam
- Drug Susceptibility testing
Which TB diagnostic?
- wheal created with 0.1ml PPD
- read in 48-72 hours
- may not present for 2-8 weeks following exposure
TST
The following groups are considered TB positive if induration is…
HIV close contacts Evidence on CXR Immunosuppressed Organ Transplant
5+ mm
The following groups are considered TB positive if induration is…
recent immigrants from high TB
IVDU
Mycobacteriology lab personnel
Healthcare workers
medical conditions
< 4yo
children/adolescents exposed to adults at high risk
10+ mm
A TB test is considered positive in anybody if it is greater than…
15mm
Who should receive 2 step TB testing?
healthcare workers
What vaccine may create false positives?
BCG
Which TB test measures immune response to TB in blood?
IGRA (quantiferon gold, T-Spot)
For the IGRA test, blood is incubated ______ and response is measured
TB antigen
When would IGRA be considered instead of TST?
compliance/return
BCG vaccination
Can IGRA differentiate between TB disease and latent TB?
no
What 4 features on CXR can help diagnose TB?
- hilar LAD
- effusion/infiltrate
- cavitation
- miliary pattern
Can CXR determine active vs inactive disease?
no
The following CXR finding indicates…
dense nodule/lesions with calcification
latent TB
The following CXR for TB finding indicates…
cavities
infiltrates
LAD
reactivation of latent TB
Where are abnormalities typically seen in the lungs in TB?
apical/posterior upper lobes
superior lower lobe
The following on CXR for TB indicates…
- calcified parenchymal granuloma
- ipsilateral calcified hilar lymph node
Healed primary pulmonary TB (Ranke Complex)
What is used for bacteriologic study in diagnosing TB?
sputum collection
What is the protocol for sputum collection in TB?
3 specimens 8-24 hr apart
1 sample in the morning
What type of bacteriologic study for TB?
Easy/quick
supports Dx, doesn’t confirm
smear
acid fast bacilli (AFB)
What type of bacteriologic study for TB?
supports dx, doesn’t confirm
used if high suspicion
cytology
Nucleic acid amplification (NAA)
What is the gold standard for diagnosis of TB, but takes weeks for results?
culture
You receive a positive AFB and NAA. What action occurs next?
begin treatment, presume TB
If culture is positive for TB, how do you proceed?
treatment and drug susceptibility testing
If culture is negative, but TB is still suspected, how do you proceed?
treat and monitor response
What is hallmark on biopsy for TB?
necrotizing granuloma
Which TB test has the following features?
- automated NAA test
- uses disposable cartridge
- identifies TB DNA and rifampin resistane
Xpert MTB/RIF assay
What are the advantages to Xpert MTB/RIF assay?
2 hours
minimal training
What are the disadvantages for Xpert MTB/RIF assay?
cost
doesn’t replace AFB smear or cx
For whom is Xpert MTB/RIF assay indicated?
patients with < 3 days of therapy
TB must be reported within ______ hours
24 hours
What are the 4 first line drugs for TB?
Rifampin
isoniazid
pyrazinamide
ethambutol
What must be part of administering TB drugs?
direct observed treatment