Mycobacterium tuberculosis: Difference between revisions

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Mycobacterium tuberculosis
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** Improvement in symptoms
 
** Improvement in symptoms
   
=== IRIS ===
+
=== Immune reconstitution inflammatory syndrome (IRIS) ===
   
=== DILI ===
+
=== Drug-induced liver injury (DILI) ===
 
* Most common complication leading to treatment interruption, with a mortality of 6-12% if drugs are not stopped
 
* Most common complication leading to treatment interruption, with a mortality of 6-12% if drugs are not stopped
 
* Rif > INH > PZA
 
* Rif > INH > PZA

Revision as of 12:35, 10 November 2019

  • Mycobacterium tuberculosis causes tuberculosis
  • Most commonly pulmonary TB but extrapulmonary tuberculosis is possible (including adenitis, gastrointestinal TB, pericarditis, meningitis)
  • Standard treatment for susceptible TB is RIPE x2mo then RI x4mo

Background

Microbiology

Epidemiology

  • Reinfection accounts for ~40% of active tuberculosis in endemic countries
  • Latent tuberculosis in ~30% of the global population

Clinical Presentation

Classification

  • Primary vs. reactivation vs. reinfection
  • Latent vs. active

Primary tuberculosis

  • Primary tuberculosis is usually asymptomatic
  • Possible presentations include mild URTI with cough and/or fever
  • May be seen on CXR as infiltrate in mid-lung zones with hilar adenopathy
  • Ghon complex, especially in children
  • May progress in children and the immunocompromised patients
  • Immunological phenomena
    • Erythema nodosum
    • Phlyctenular conjunctivitis
    • Erythema induratum

Pulmonary 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

Extra-pulmonary tuberculosis

Latent tuberculosis

Investigations

  • Radiography: chest x-ray with or without CT chest
  • Microbiology:
    • Samples can include routine or induced sputum (x3) or bronchoscopy, or tissue sample
    • Spontaneous sputum should include at least one morning sputum, ideally
    • Acid-fast bacillus culture of sputum x3 is about 70% sensitive, and PCR (ANTB) x1 is about 75% sensitive

Management

  • Standard HREZ x2mo then HR x4mo
    • Isoniazid 5mg/kg/d, max 300mg daily
    • Rifampin 10mg/kg/d
    • Pyrazinamide 25mg/kg/d, max 2g daily
    • Ethambutol 20mg/kg/d, max 1.2g daily
    • Pyridoxine 25 mg po daily
  • Airborne precautions until:
    • Treated for at least 2 weeks
    • 3x negative sputum smears
      • Collected at 8- to 24-hour intervals, including one early morning collection
    • Improvement in symptoms

Immune reconstitution inflammatory syndrome (IRIS)

Drug-induced liver injury (DILI)

  • Most common complication leading to treatment interruption, with a mortality of 6-12% if drugs are not stopped
  • Rif > INH > PZA
  • Most patients can have the same TB drugs reintroduced without recurrence of DILI, though recurrence can be delayed
  • Procedure
    • Hold if ALT >120 and symptoms, if ALT >200 even without symptoms, or bili >2x ULN
    • Switch to second-line meds
    • Reintroduce the original drugs once AST & ALT are <2x ULN
    • Only rechallenge with pyrazinamide if it was a mild case

Adherence to Treatment

Further Reading