Mycobacterium tuberculosis causes tuberculosis, most commonly pulmonary but can affect any organ

Classification

Epidemiology

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
Recent primary tuberculosis
- Immunological phenomena
  - Erythema nodosum
  - Phlyctenular conjunctivitis
Recent or active tuberculosis
- Erythema induratum
Reactivation tuberculosis
- Poorly-defined clinical course
- Usually reactivates in lung apices
Active tuberculosis
- Cough and fever for more than two weeks
- Cough and HIV infection
Extra-pulmonary tuberculosis
- Pleural tuberculosis is most common
- Scrofula (cervical lymph node infection) next-most common
- Tuberculous meningitis
- Tuberculous pericarditis
- Renal tuberculosis
- Abdominal tuberculosis
- Gastrointestinal tuberculosis

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
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

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