Tuberculosis Flashcards
What organisms are in mycobacterium tuberculosis complex? [7]
M. tuberculosis.
M. africanum.
M. bovis (commonly associated with intestinal tract TB via consumption of unpasteurized dairy products).
M. canetti (cases seen in the Horn of Africa).
M. pinnipedii (exposure to seals).
M. microti (a rodent pathogen).
Bacillus Calmette–Guérin (BCG).
What is multidrug resistant TB?
Resistance to both isoniazid (INH) and rifampin (RIF).
What is extensively drug-resistant (XDR) TB?
MDR AND Resistance to any fluoroquinolone (FLQ) AND Resistance to at least one of the three injectable agents (amikacin, capreomycin, or kanamycin).
Risk factors for progression in TB? [7]
Diabetes Intravenous drug use, Intestinal bypass TNF-α inhibitors [high risk] CXR abnormalities c/w prior inadequately treated infection HIV [high risk] or other immunosuppression End-stage renal disease Recent TB infection [high risk] Silicosis
DITCHERS
Is TB infection more likely to become latent or active?
Latent [90%]
Risk of LBTI infection to become active if HIV positive vs HIV negative
5-10% life long if HIV negative
5-10% per hear if HIV positive
In whom is a PPD of 5 mm or more positive? [4]
- HIV
- Close contact with active TB case
- CXR consistent with TB
- Immunosuppressed (patients with transplant or on prednisone ≥15 mg/day for >3 weeks), receiving anti-tumor necrosis factor (TNF) agents
In whom is a PPD of 10 mm or more positive? [7]
- Dialysis
- diabetes
- IV drug users
- lymphoma/leukemia
- head/neck cancer
- foreign born from countries of higher incidence
- high-risk patients (i.e., healthcare workers, incarcerated, homeless, nursing home or long-term care facility residents, microbiology lab personnel)
In whom is a PPD of 15 mm or more positive?
Healthy persons without risk factors for TB
What might cause a false negative PPD? [5]
- Live virus vaccinations
- Hypoproteinemia
- Lymphoproliferative disorders
- Old age
- Use of immunosuppressants (corticosteroids),
improper administration, interpretation, or storage
Difficulty with treating LTBI in pregnancy regarding medication side effects?
Increased risk of hepatotoxicity due to INH, extending up to 3 months postpartum.
When should those who are pregnant be treated for LTBI? [3]
- recently exposed
- those living with HIV
- significant immunosuppression.
Approved treatments for LTBI? [5]
- INH + RPT once a week for 3 months [best adherance]
- RIF daily 4 months
- INH daily 6 months
- INH daily 9 months
- INH twice weekly 6–9 months
Treatment of LTBI if exposed to MDR strain of TB?
Fluoquinolone + Ethambutol for 1 year
Who should get baseline LFTs and bilis done prior to TB treatment? [5]
Underlying liver disease. Active alcohol consumption. Concomitant hepatotoxic drugs. Pregnancy, up to 3 months postpartum. People living with HIV.
How does primary TB infection typically look in the lungs [lobe involvement, lymphnodes, pleural effusion]?
Mid-lower lobe disease in >80% of patients
Hilar adenopathy in 2/3 of patients (R>L)
Pleural effusion in 1/3 of patients
How does reactivation TB present?
Fever and night sweats are seen in 50% of cases.
Upper lobe involvement with cavitation
Hemoptysis is seen in 25%
Cavitation is more common (20%–40%) than in primary TB
What is Rasmussen’s aneurysm?
Aneurysm in the setting of a cavitation
How is TB pleuritis diagnosed?
- Lymphocytic predominant exudative effusion with an adenosine deaminase (ADA) >40 IU/L
- Presence of caseating granulomas on pleural biopsy (>70% of cases).
Role of AFB smear, NAAT, pleural fluid culture, and pleural fluid biopsy culture in the diagnosis of TB pleuritis?
AFB smear: <10% sensitivity
Fluid Culture: <30% sensitivity
NAAT: 45% sensitivity
Pleural fluid biopsy: 40-80% sensitivity
Granulomatous pleuritis ddx [5]
TB in 95% of cases rheumatoid arthritis fungal infection tularemia sarcoidosis
What is endobronchial TB?
Infection of the tracheobronchial tree is more commonly seen in extensive TB disease as extension from lung focus
Presentation of endobronchial TB?
Barking productive cough, wheezing, rhonchi and, rarely, lithoptysis.
Complications of endobronchial TB? [3]
Bronchial stenosis is present in 90%
bronchial ulceration (hemoptysis)
perforations (fistulas)
Endobronchial TB diagnosis/work up
CXR negative in up to 20%
CT would show endobronchial lesions
Definitive diagnosis is via culture from bronchoscopy
What examination should every patient with miliary TB have done?
funduscopy
High yield biopsy sites for patients with miliary TB? [4]
bone marrow, liver, lymph nodes, pleura/bronchi.
How is TB lymphadenitis diagnoised?
FNA first with AFB smear, culture, and histologic evaluation
Excisional biopsy if negative