Tuberculosis Flashcards
Rifampicin mechanism of action
Inhibits bacterial DNA dependent RNA polymerase preventing transcription of DNA into mRNA
Potent liver enzyme inducer; causes hepatitis, orange secretions, and flu-like symptoms.
Isoniazid mechanism of action
Inhibits mycolic acid synthesis
Causes peripheral neuropathy; prevent with pyridoxine (Vitamin B6), hepatitis, and agranulocytosis. Liver enzyme inhibitor.
Pyrazinamide mechanism of action
Converted by pyrazinamidase into pyrazinoic acid which inhibits fatty acid synthase (FAS) I
Causes hyperuricaemia leading to gout, arthralgia, myalgia, and hepatitis.
Ethambutol mechanism of action
Inhibits the enzyme arabinosyl transferase which polymerizes arabinose into arabinan
Causes optic neuritis; check visual acuity before and during treatment. Dose needs adjusting in patients with renal impairment.
What is latent tuberculosis?
Latent tuberculosis is a condition where patients are asymptomatic and non-infectious.
How is latent tuberculosis diagnosed?
Diagnosis is typically made through a positive tuberculin skin test or Interferon-Gamma Release Assay (IGRA) combined with a normal chest x-ray.
What are the treatment options for latent tuberculosis according to NICE?
The treatment options are:
1. 3 months of isoniazid (with pyridoxine) and rifampicin, or
2. 6 months of isoniazid (with pyridoxine).
What factors influence the choice of treatment regimen for latent tuberculosis?
The choice of regimen is based on the person’s clinical circumstances, including age and risk factors for hepatotoxicity.
Who should receive 3 months of isoniazid and rifampicin?
People younger than 35 years should receive 3 months of isoniazid (with pyridoxine) and rifampicin if hepatotoxicity is a concern.
Who should receive 6 months of isoniazid?
6 months of isoniazid (with pyridoxine) is recommended if there are concerns about interactions with rifamycins, such as in people with HIV or those who have had a transplant.
Can people with latent tuberculosis spread the disease?
No, people with latent tuberculosis cannot pass the disease on to others.
What are the risk factors for developing active tuberculosis?
Risk factors include:
- silicosis
- chronic renal failure
- HIV positive
- solid organ transplantation with immunosuppression
- intravenous drug use
- haematological malignancy
- anti-TNF treatment
- previous gastrectomy.
What is the standard therapy for treating active tuberculosis during the initial phase?
The initial phase lasts for the first 2 months and includes Rifampicin, Isoniazid, Pyrazinamide, and Ethambutol.
The 2006 NICE guidelines recommend giving Ethambutol routinely.
What is the standard therapy for treating active tuberculosis during the continuation phase?
The continuation phase lasts for the next 4 months and includes Rifampicin and Isoniazid.
What is the treatment for latent tuberculosis?
The treatment options are 3 months of Isoniazid (with pyridoxine) and Rifampicin or 6 months of Isoniazid (with pyridoxine).
How are patients with meningeal tuberculosis treated?
Patients with meningeal tuberculosis are treated for a prolonged period of at least 12 months with the addition of steroids.
What is directly observed therapy in tuberculosis management?
Directly observed therapy with a three times a week dosing regimen may be indicated for homeless people with active tuberculosis, patients likely to have poor concordance, and all prisoners with active or latent tuberculosis.
What is immune reconstitution disease?
Immune reconstitution disease occurs typically 3-6 weeks after starting treatment and often presents with enlarging lymph nodes.
What are the adverse effects of Rifampicin?
Rifampicin is a potent liver enzyme inducer and can cause hepatitis, orange secretions, and flu-like symptoms.
What are the adverse effects of Isoniazid?
Isoniazid can cause peripheral neuropathy (prevent with pyridoxine), hepatitis, and agranulocytosis.
What are the adverse effects of Pyrazinamide?
Pyrazinamide can cause hyperuricaemia leading to gout, arthralgia, myalgia, and hepatitis.
What are the adverse effects of Ethambutol?
Ethambutol can cause optic neuritis; visual acuity should be checked before and during treatment.
What is the standard therapy for treating active tuberculosis during the initial phase?
The initial phase lasts for the first 2 months and includes Rifampicin, Isoniazid, Pyrazinamide, and Ethambutol.
The 2006 NICE guidelines recommend giving Ethambutol routinely.
What is the standard therapy for treating active tuberculosis during the continuation phase?
The continuation phase lasts for the next 4 months and includes Rifampicin and Isoniazid.