What is the treatment for intestinal tuberculosis in patients with or without compromised immune systems, such as Human Immunodeficiency Virus (HIV)/Acquired Immunodeficiency Syndrome (AIDS), impaired renal (kidney) function, or impaired hepatic (liver) function?

Treatment of Intestinal Tuberculosis

Intestinal tuberculosis should be treated with the standard 6-month four-drug regimen: isoniazid, rifampin, pyrazinamide, and ethambutol for 2 months (intensive phase), followed by isoniazid and rifampin for 4 months (continuation phase), with the same dosing and monitoring as for pulmonary tuberculosis. 1

Standard Treatment Regimen

Intensive Phase (First 2 Months)

• Isoniazid: 5 mg/kg (maximum 300 mg) daily 1, 2
• Rifampin: 10 mg/kg (maximum 600 mg) daily 1, 2, 3
• Pyrazinamide: 25-35 mg/kg (maximum 2.0 g) daily 1, 2
• Ethambutol: 15 mg/kg daily 1, 4

Continuation Phase (Months 3-6)

• Isoniazid: 5 mg/kg (maximum 300 mg) daily 1
• Rifampin: 10 mg/kg (maximum 600 mg) daily 1

This 6-month regimen applies to all forms of extrapulmonary tuberculosis, including intestinal disease, and is recommended by the American Thoracic Society 1, 5. The regimen is effective for both HIV-infected and uninfected patients 5.

Special Populations

HIV/AIDS Patients

• Use the same 6-month regimen but with critical attention to clinical and bacteriologic response 5
• Monitor CD4 count and HIV RNA load at baseline 6
• Be aware of significant drug interactions between rifamycins and antiretroviral medications, particularly protease inhibitors and non-nucleoside reverse transcriptase inhibitors 6
• Rifabutin may be substituted for rifampin with appropriate dose adjustments when drug interactions are problematic 6
• If response is slow or suboptimal, prolong therapy on a case-by-case basis 5

Hepatic Impairment

• Measure baseline liver function tests (AST, ALT, bilirubin) before starting treatment 2
• Screen for hepatitis B and C in high-risk patients (injection drug users, those from endemic regions, HIV-positive patients) 2

For advanced liver disease or baseline ALT >3× upper limit of normal:

• Omit pyrazinamide and use isoniazid, rifampin, and ethambutol for 2 months, followed by 7 months of isoniazid and rifampin (total 9 months) 2

If hepatotoxicity develops during treatment (AST/ALT >5× normal or any bilirubin elevation):

1. Stop all hepatotoxic drugs (rifampin, isoniazid, pyrazinamide) immediately 1, 2
2. Wait for liver function to normalize 2
3. Reintroduce drugs sequentially: 1
   • Start isoniazid at 50 mg/day, increase to 300 mg/day after 2-3 days
   • Add rifampin at 75 mg/day after 2-3 days without reaction, increase to full dose
   • Add pyrazinamide at 250 mg/day, increase to full dose

Alternative for patients who cannot tolerate isoniazid:

• Use rifampin, ethambutol, and a fluoroquinolone (with or without an injectable agent) for 12-18 months 2

Renal Impairment

• Evaluate renal function before starting treatment 1
• Avoid streptomycin and ethambutol in renal insufficiency if possible 1
• If these drugs must be used, monitor serum concentrations and adjust doses accordingly 1

Critical Monitoring Requirements

Baseline Evaluation

• Obtain cultures for drug susceptibility testing (isoniazid, rifampin, ethambutol, pyrazinamide) 6
• HIV testing in all patients 6
• Liver function tests (AST, ALT, bilirubin) 6
• Renal function tests 6
• Visual acuity (Snellen test) and color discrimination for patients on ethambutol 6
• Weight for dose calculation 6

During Treatment

• Monthly monitoring for:

  • Weight (adjust doses if needed) 6
  • Adherence assessment 6
  • Symptom improvement (fever, abdominal pain, weight loss) 6
  • Adverse effects (jaundice, dark urine, nausea, vomiting, abdominal pain, rash, neuropathy) 6
  • Visual disturbance inquiry and color discrimination tests (for ethambutol) 6

• Liver function tests only if baseline abnormalities exist, symptoms of hepatotoxicity develop, or patient has risk factors (chronic alcohol use, viral hepatitis, HIV, other hepatotoxic medications) 6

Drug Resistance Considerations

If drug resistance is suspected or confirmed:

• Isoniazid-resistant TB: Use rifampin, pyrazinamide, and ethambutol for 6-9 months or 4 months after culture conversion 6
• Rifampin-resistant TB: Use isoniazid, streptomycin, pyrazinamide, and ethambutol for 2 months, followed by isoniazid, streptomycin, and pyrazinamide for 7 months (total 9 months) 6
• Multidrug-resistant TB (resistant to both isoniazid and rifampin): Consult a TB specialist; treatment typically includes an aminoglycoside and fluoroquinolone for 24 months after culture conversion 6

Important Clinical Pitfalls

• Never use rifampin intermittently (twice weekly) at doses >600 mg, as this increases risk of flu syndrome, hematopoietic reactions, and renal failure 3
• Never stop treatment prematurely in asymptomatic patients with transaminase elevations <5× normal without bilirubin elevation, as this risks treatment failure and drug resistance 2
• Never ignore bilirubin elevation—any rise mandates immediate cessation of hepatotoxic drugs regardless of transaminase levels 2
• Warn patients about orange/red discoloration of urine, sweat, tears, and potential permanent staining of soft contact lenses 3
• Directly observed therapy (DOT) is strongly recommended to ensure adherence and prevent treatment failure 6, 5

Management of Treatment Interruptions

During intensive phase:

• If lapse <14 days: Continue to complete planned doses (within 3 months) 6
• If lapse ≥14 days: Restart treatment from the beginning 6

During continuation phase:

• If received ≥80% of doses: Continue until all doses completed 6
• If received <80% of doses and lapse <3 months: Restart from beginning if cannot complete within recommended timeframe 6
• If lapse ≥3 months: Restart treatment from the beginning 6