Pulmonary tuberculosis

From IDWiki

Background

Microbiology

Clinical Manifestations

  • Presents as reactivation of latent infection months or years after primary tuberculosis
  • Subacute or chronic cough (at least 2 to 3 weeks) eventually becoming productive and occasionally involving hemoptysis
    • Should be suspected in any patient with cough and HIV infection
  • Constitutional symptoms, with fevers, night sweats, and unexplained weight loss
  • Usually from reactivation of latent tuberculosis infection, and usually reactivates in lung apices
  • May transiently improve with partially-active antibiotics such as fluoroquinolones

Investigations

  • Spontaneous sputum, induced sputum, or bronchoalveolar lavage specimens should be sent for
    • Acid-fast staining of a smear
    • Culture
    • PCR
  • Chest x-ray may show signs of prior tuberculosis, including dense pulmonary nodules (with or without calcification) which can be hilar or upper lobe; small nodules with or without scarring/fibrosis in the upper lobes; upper lobe volume loss or bronchiectasis; pleural scarring

Management

  • Empiric treatment for suspected drug-susceptible tuberculosis is RIPE x2mo then RI x4mo
    • Isoniazid 5mg/kg/d, max 300mg daily, with pyridoxine 25 mg po daily
    • Rifampin 10mg/kg/d
    • Pyrazinamide 25mg/kg/d, max 2g daily
    • Ethambutol 20mg/kg/d, max 1.2g daily, which can be dropped once susceptibility testing shows that it is pan-susceptible
  • Standard duration for uncomplicated disease is 6 months total, though it is extended if high risk of relapse (see Special Populations, below)
  • Treatment for multidrug-resistant tuberculosis is discussed separately

Special Populations

  • For the elderly, or those at elevated risk of hepatotoxicity: can do induction phase without pyrazinamide and extend continuation phase to 7 months (from 4)
  • For pregnant women: can consider dropping pyrazinamide and extending the course by 3 months, but if there is severe disease then likely should follow standard treatment
  • For high risk of relapse, including extensive or cavitary disease in the first 2 months of treatment, culture-positivity after 2 months of treatment, or cavitary disease on CXR at end of treatment: the consolidation phase should be extended by 3 months (to 9 months total treatment)
  • For severe liver disease:

Adjunctive Therapies

  • The addition of metformin to the induction regimen has been shown to speed resolution of radiographic findings, such as cavitations[1]
    • Metformin 500 mg p.o. daily for 1 week then 1000 mg p.o. daily for 7 weeks
    • No difference in conversion of sputum culture

Infection Control

  • Airborne precautions until:
    • Treated for at least 2 weeks and symptoms are clearly improving
    • 3x negative sputum smears
    • They can be discharged home when clinical improvement, drug-resistant TB is not suspected and there is no contraindication for home isolation
  1. Chandrasekaran Padmapriydarsini, Megha Mamulwar, Anant Mohan, Prema Shanmugam, N S Gomathy, Aarti Mane, Urvashi B Singh, Nathella Pavankumar, Abhijeet Kadam, Hemanth Kumar, Chandra Suresh, Devaraju Reddy, Poornaganga Devi, P M Ramesh, Lakshmanan Sekar, Shaheed Jawahar, R K Shandil, Manjula Singh, Jaykumar Menon, Randeep Guleria, the METRIF Team, Randomized Trial of Metformin With Anti-Tuberculosis Drugs for Early Sputum Conversion in Adults With Pulmonary Tuberculosis, Clinical Infectious Diseases, Volume 75, Issue 3, 1 August 2022, Pages 425–434, https://doi.org/10.1093/cid/ciab964