Day #111 - TB Pleuritis

Today we talked about a great case.

There is a *great* free resource called the Canadian Tuberculosis Standards available here.

First we talked about the diagnosis and treatment of latent tuberculosis infection.

Diagnosis:

• Positive mantoux test
  
  • Interpret in context of patient's history
    
    • less than 5mm - negative (or false negative in immunosuppressed or very ill patient)
    • 5mm-10mm - HIV, close contact with known case, chest xray evidence of old TB as fibronodular disease, children, immunosuppression (chemo, TNF alpha, high dose steroids)
    • Greater than 10 - positive for all others
    • Increase in 6 from previous known positive.
      
  • BCG -- only consider BCG as the cause of a TST if it was given after 12 months of age to a patient from a low risk country and does not have radiographic evidence of old TB
• Can consider inferferon based assay, though this is not the standard
  
• Evidence of prior tuberculosis on imaging
• No evidence of active disease

Treatment:

• Tend to treat people who are at the highest risk of re-activating or those with the lowest risk of drug side-effects
  
  • High risk includes: HIV, organ transplant, TNF alpha inhibitors and other immunosuppression
  • Risk in health normal person is ~ 5% in first 2 years and 10% over the lifetime
  • Immigration and reactivation risk
    
• INH 300mg PO OD x 9 months with Vitamin B6 25mg po OD
• Alternative (not as good): RIFAMPIN 600mg po OD x 4 months

We then talked about diagnosis and treatment of TB pleuritis

Diagnosis:

Acute to subacute illness (2/3 present less than 1 month) with fever, pleuritic chest pain, minimally productive cough. Unilateral effusion.

• Exudative effusion
• pH usually ~ 7.4
• Glucose usually normal
  
• Lymphocytic pleocytosis (though can be neutrophils early)
  
• Usually less than 5% mesothelial cells
• AFB stain less than 10%
• Culture ~ 30% (yield may improve by inoculating into special culture media)
  
• PCR positive in 90-100% of culture positive but only 30-60% of culture negative
• Sputum positive in ~ 50%
• Pleural biopsy shows either granulomas or AFB or is culture positive in up to 95%
  

• Measurement of Adenosine Deaminase
• The future: Other novel tests

Treatment:

• INH, RIF, ETH (add PZA if sputum positive, sick, bilateral effusions, other extrapulmonary disease) x 2 months then if INF/RIF sensitive INF/RIF to complete 6 months
• Adjuvant steroids are not clearly indicated
  
• Effusion may take up to 6 months post treatment to resolve.