Mycobacterium tuberculosis
From IDWiki
- 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
Classification
- Primary vs. reactivation vs. reinfection
- Latent vs. active
Epidemiology
- Reinfection accounts for ~40% of active tuberculosis in endemic countries
- Latent tuberculosis in ~30% of the global population
Clinical Presentation
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
- Pleural tuberculosis is most common extrapulmonary site
- Scrofula (cervical lymph node infection) next-most common
- Tuberculous meningitis
- Tuberculous pericarditis
- Renal tuberculosis
- Abdominal tuberculosis
- Gastrointestinal tuberculosis
Latent tuberculosis
- Refers to chronic latent infection contained within granulomas that may reactivate in the future
- Refer to Latent tuberculosis infection
Investigations
- AM sputum for acid-fast bacilli x3
- About 70% sensitive
- ANTB (PCR)
- 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
- 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
IRIS
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
- Refer to Let's Talk TB
