In our #AMreport @WCHospital, we reviewed a case of active pulmonary tuberculosis. In our case, the patient presented with a two week history of a non-productive cough as the only symptom. A chest x-ray done revealed findings similar to attached image (figure 1: courtesy of wikipedia). The patient had sputum positive for acid fast bacilli and was treated with RIPE regimen.

Learning points:

1. What is TB?
2. What is difference between active and latent TB?
3. What is RIPE regimen?
4. Risk factors for TB.

What is TB?

• TB is caused by Mycobacterium tuberculosis (figure 2).
• Transmission is primarily airborne by inhalation.
  • Lungs are primary focus of infection as a result.

What is the difference between active and latent TB?

• Latent TB infection (LTBI)
  • Asymptomatic (i.e manifestations of the disease are contained by immune system)
  • Can be detected by tuberculin skin test (TST) or interferon-gamma release assay (IGRA)
    • false-positive results  can occur in patients who have previously received Bacillus Calmette–Guérin (BCG) vaccine after infancy and many times.
    • IGRA is a more specific test for the above-mentioned populations
• Active TB infection
  • Symptomatic: fever, night sweats, cough, fatigue, weight loss for a period of >2 weeks (i.e manifestations of the disease are NOT contained by immune system).
  • TST and IGRA have no role in active TB.
    • Both test have poor sensitivity and specificity in active disease.
  • Patients should be isolated in negative pressure rooms if there is a strong suspicion of active TB.
  • Arrange for 3 morning sputum for AFB.
    • If 3 consecutive sputum samples are negative for AFB then the patient can be removed from isolation.

What is the RIPE regimen?

•   RIPE regimen or also known as quadruple therapy consists of three bactericidal and one bacteriostatic agent.
• Patients with active TB should received RIPE therapy until susceptibilty results are available.
• Quick memory aid for the bactericidal  agents:
  • TB goes to the grave with RIP (Rifampin, Isoniazid, Pyrazinamide)
    
  • Ethambutol is bacteriostatic agent with the main complication being optic neuritis
  • Rifampin has the main side effects of hepatotoxicity and produces orange appearing bodily fluids (eg. sweat, urine)
  • Isoniazid has the main complication of peripheral neuropathy and hepatoxicity.
    • Patients must supplemented with pyrodoxine (B6) 10-25 mg PO daily to decrease risk of neuropathy.
  • Pyrazinamide has side effects not limited to GI intolerance and liver injury.

Risk Factors for TB

~2 billion worldwide affected with TB.

• Birth and residence in an endemic area
• Institutionalized individuals (close contact dwelling)
• Healthcare workers.
• HIV, immunosuppression.
• Chronic kidney disease, diabetes.
• Alcohol abuse and smoking.

 

References:

1. Canadian TB Standards 7th Edition 

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-B