What are high risk groups for TB? What is considered positive on a tuberculin skin test (TST)?
- HIV or immunosuppressed
- Close contact of TB pt
- Abnormal CXR
Positive > 5mm
What are moderate risk groups for TB? What is considered positive on a tuberculin skin test (TST)?
- Recently infected (under 2 yrs) = recent converter
- High risk medical conditions: DM, cancer of head/neck, lung, organ transplant
Positive > 10 mm
What are low risk groups for TB? What is considered positive on a tuberculin skin test (TST)?
None of the other conditions (HIV/immunosuppressed, close contact, abnromal CXR, high risk medical conditions like DM, cancer, organ transplant...)
Positive > 15 mm
What is the natural history/course of LTBI in an HIV negative pt?
- No further problem with no evidence of active disease (90%)
- Primary infection is not well contained and active disease develops within 2 years (lower lobe, hilar, pleural) (5%)
- "Reactivation of previously contained, dormant TB (usually > 2 years after primary infection (5%)
What is the natural history/course of LTBI in an HIV pt?
Risk for active TB: 7-10% per year
Treatment of LTBI?
- Standard therapy: 4 first line drugs
---- Intensive phase = RIPE (Rifampin, Isoniazid, Pyrazinamide, Ethambutol) for 2 mo
----- Continuation phase = RI for 4 mo
- Provide safest, most effective therapy in shortest time: decrease infectivity, morbidity mortality
- Adherence to therapy- DOT, in all
- Major determinant of outcome is adherence and completion
- Children treated same as adults
- Extrapulmonary TB treated the same
- Contact investigation = key to dz prevention (pic 2)
What are risks for active TB?
- Previously untreated TB (stable, fibrotic pulmonary lesion)
- Use of anti-TNF, chronic steroids
- Malignancy – head and neck, lung
- Chronic renal failure
- Diabetes mellitus
- Active smoker
- Post gastrectomy
Characteristics of primary TB (pathologically/anatomically)?
- Lower lobe involvement
- Pneumonic pattern
- Hilar LAD
- Pleural effusion
Characteristics of reactivation TB (who gets it, sites, anatomy)
- Majority of pts with active TB
- Endogenous reactivation of latent infection
- Occurs in sites that were disseminated during the primary infection
- Most common site = apical posterior segment of lung (80%)
What clinical features aid in the diagnosis of TB?
- Risk factors for exposure
- Signs and symptoms: usually chronic (wks - mos) and non-specific
- Persistant cough
- Malaise, fatigue
- Weight loss, anorexia
- Night sweats
How can the microbiologic diagnosis be made for TB?
Acid fast stain: Ziehl Neelsen or auramine fluorescence
- Three sputum specimens ~50% positive
- Culture: 2-6 weeks
- Drug susceptibility: 1-2 weeks
- Nucleic acid amplification – PCR based
- Drug susceptibility – detect gene mutation
How can therapy be monitored?
Monthly sputum culture until negative
- 80% are culture negative in 2 months
- If positive > 2 months, repeat susceptibility
Serial CXR are not recommended
- End of treatment CXR – future comparison
Clinical evaluation monthly
- Adverse reactions and adherence to therapy
Treat co-morbidity – DM, COPD, HIV
- Emerging threats to global TB control
- Treatment of LTBI – important role in TB elimination
- Clinical presentation of TB is varied
- Close clinical follow up and partnership with public health department – ensure completion of treatment
- Clinical manifestations of pneumonia are non-specific
- Epidemiologic factors are useful in narrowing the possible etiologic agents
- Treatment should be directed to the most likely pathogen(s) and initiated without delay
- Clinical features that predict mortality help guide decision for hospitalization