Tuberculosis Flashcards
What are the two phases of the standard treatment of active tuberculosis?
- Initial phase (4 drugs)
2. Continuation phase (2 drugs)
What are the names of the two regimens recommended for the treatment of TB in the UK?
- Unsupervised
- Supervised (directly observed therapy, DOT)
The choice of either regimen is dependent on a risk assessment to identify if an individual needs enhanced case management.
What 4 drugs are used in the standard treatment of TB during the initial phase of therapy?
- Rifampicin
- Ethambutol hydrochloride
- Pyrazinamide
- Isoniazid (with pyridoxine hydrochloride)
Continue for 2 months
How long is the initial phase of TB therapy?
2 months
4 drugs are used: rifampicin, ethambutol hydrochloride, pyrazinamide and isoniazid (with pyridoxine hydrochloride)
Do you wait for culture results to come back before starting initial therapy of TB if the patient has clinical signs and symptoms consistent with a TB diagnosis?
NO - start immediately
Also consider completing the standard treatment even if subsequent culture results are negative
A patient has clinical signs and symptoms consistent with a TB diagnosis, you start therapy before the culture results come back. If the culture results are negative do you continue to complete the standard treatment?
Yes (consider completing the standard treatment even if subsequent culture results are negative)
Which 2 drugs are used in the standard continuation phase of TB therapy?
- Rifampicin
- Isoniazid (with pyridoxine hydrochloride)
For 4 months in individuals with active TB without CNS involvement.
For 10 months in individuals with active TB with CNS involvement
A patient has completed the initial phase of TB therapy, how long is the continuation phase if the patient has active TB WITHOUT CNS involvement?
4 months
A patient has completed the initial phase of TB therapy, how long is the continuation phase if the patient has active TB WITH CNS involvement?
10 months
Which patients can have the unsupervised TB treatment regimen?
Individuals who are likely to take antituberculosis drugs reliably and willingly without supervision
In the supervised TB treatment regime, what is the minimum number of times the patient needs to come in for direct observation?
3 times weekly (if daily direct observed therapy, DOT, is not available)
Which individuals are offered the supervised (directly observed therapy, DOT) TB treatment? (9)
- Current risk or history of non-adherence
- Previously been treated for tuberculosis
- History of homelessness, drug or alcohol misuse
- In prison or a young offender institution, or have been in the past 5 years
- Major psychiatric, memory or cognitive disorder
- In denial of the TB diagnosis
- Multi-drug resistant TB
- Request directly observed therapy after discussion with the clinical team
- Too ill to self-administer treatment
If a patient has Tb with CNS involvement, which drug should be added to their treatment in addition to anti-TB medications?
High dose dexamethasone or prednisolone
Slowly withdrawn over 4-8 weeks
What three indications to refer a patient with TB with CNS involvement to surgery?
- Raised intracranial pressure
- Spinal TB with spinal instability
- Spinal TB with evidence of spinal cord compression
What drug should be given in addition to anti-TB medication for a patient with active pericardial TB?
High dose of oral prednisolone
Slowly withdrawn over 2-3 weeks
Which individuals with latent tuberculosis are at increased risk of developing active TB? (4)
- HIV-positive
- Diabetic
- Injecting drug users
- Receiving treatment with an anti-tumor necrosis factor alpha inhibitor
What is the age cut off for close contacts of pulmonary or laryngeal TB to be tested for latent TB?
Close contacts under 65 years of age should be tested for latent TB
Close contact = prolonged, frequent or intense contact, e.g. household contacts or partners
Who should drug treatment be offered to if they are close contacts of TB?
All individuals under 65 years with evidence of latent TB, if the close contact has suspected infectious or confirmed active pulmonary or laryngeal drug-sensitive TB
What is the treatment for latent TB? (2 regimens)
3 months of isoniazid (with pyridoxine hydrochloride) and rifampicin
OR
6 months of isoniazid (with pyridoxine hydrochloride)
Individuals aged 35 to 65 years with latent TB should only be offered treatment if (?) is not a concern
hepatotoxicity
Individuals aged (?) to (?) years with latent TB should only be offered treatment if hepatotoxicity is not a concern
35-65 years
What is the treatment for individuals aged under 35 years with latent TB and concern of hepatotoxicity (based on liver function - transaminase levels, and risk factors)?
3 months of isoniazid (with pyridoxine hydrochloride) and rifampicin
What is the preferred treatment of latent TB in individuals with HIV or who previously had a transplant?
6 months of isoniazid (with pyridoxine hydrochloride)
Because interaction with rifamycins are a concern
What is the definition of a treatment interruption in the treatment of TB?
A break in antituberculosis treatment of at least 2 weeks (during the initial phase)
OR
Missing more than 20% of prescribed doses
Following TB treatment interruption due to drug-induced hepatotoxicity, when should anti-TB therapy be restarted? (3 criteria)
Once AST and ALT levels fall below twice the upper limit of normal \+ Bilirubin levels in normal range \+ Hepatotoxic symptoms have resolved
Anti-TB therapy should be sequentially re-introduced at previous full doses over a period of no more than 10 days
Following TB treatment interruption due to drug-induced hepatotoxicity, how should you restart therapy?
Sequentially re-introduce anti-TB drugs at previous full doses over a period of no more than 10 days.
Start with ethambutol hydrochloride and either isoniazid (with pyridoxine hydrochloride) or rifampicin
If a patient with severe or highly infectious TB has drug-induced hepatotoxicity and need a treatment interruption, what should you consider doing?
Continue treatment with at least 2 drugs with low risk hepatotoxicity - ethambutol hydrochloride and streptomycin (with or without a fluoroquinolone antibiotic)
+
monitoring by a liver specialist
Which two anti-TB drugs have a low risk of hepatotoxicity and you can consider continuing in patients with severe or highly infectious TB who develop drug-induced hepatotoxicity?
Ethambutol hydrochloride
Streptomycin (with or without a fluoroquinolone antibiotic)
If a patient with severe or highly infectious TB has cutaneous reactions, what should you consider doing?
Continue treatment with a combination of at least 2 drugs with low risk for causing cutaneous reactions - ethambutol hydrochloride and streptomycin
+
Monitoring by a dermatologist
Which two anti-TB drugs have a low risk of cutaneous reactions and you can consider continuing in patients with severe or highly infectious TB who develop cutaneous reactions?
Ethambutol hydrochloride
Streptomycin
If TB without CNS involvement is resistant to isoniazid, what is the recommended treatment regimen?
Initial phase (2 months): Rifampicin, pyrazinamide + ethambutol hydrochloride
Continuation phase (7-10 months): Rifampicin + ethambutol hydrochloride
If TB without CNS involvement is resistant to pyrazinamide, what is the recommended treatment regimen?
Initial phase (2 months): rifampicin, ethambutol hydrochloride + isoniazid (with pyridoxine hydrochloride)
Continuation phase (7 months): Rifampicin + isoniazid (with pyridoxine hydrochloride)
If TB without CNS involvement is resistant to ethambutol hydrochloride, what is the recommended treatment regimen?
Initial phase (2 months): rifampicin, pyrazinamide + isoniazid (with pyridoxine hydrochloride)
Continuation phase (4 months): rifampicin + isoniazid (with pyridoxine hydrochloride)
If TB without CNS involvement is resistant to rifampicin, what is the recommended treatment regimen?
Offer treatment with at least 6 anti-TB drugs to which the mycobacterium is likely to be sensitive
In TB meningitis, what are the characteristics of the CSF sample? (3)
High protein
Low glucose
Lymphocytosis
What side effects are associated with isoniazid? (4)
- Peripheral neuropathy (pyridoxine hydrochloride reduces risk)
- Hepatotoxicity
- Agranulocytosis
- Inhibitor of CYP450
What side effects are associated with rifampicin? (4)
- Stains secretions orange/pink
- Hepatotoxicity
- Potent inducer of CRP450
- Flu like symptoms
- Reduces effectiveness of hormonal contraceptives
What side effects are associated with pyrazinamide? (4)
- Hyperuricaemia (causing gout)
- Arthralgia
- Myalgia
- Hepatotoxicity
What are the side effects of ethambutol hydrochloride? (1)
- Optic neuritis
Which anti-TB drug is an inhibitor of CYP450?
Isoniazid
Which anti-TB drug is an inducer of CYP450?
Rifampicin
Which anti-TB drug most commonly has the side effect of gout?
Pyrazinamide
Which anti-TB drug causes vision impairment?
Ethambutol hydrochloride
Which patients are more likely to have the side effect of ocular toxicity when taking ethambutol hydrochloride?
Those with renal impairment
Ethambutol hydrochloride should preferably be avoided in patients with renal impairment due to the risk of optic nerve damage
Dose adjustments are required if creatinine clearance is less than 30 mL/minute
Prior to starting a patient of ethambutol hydrochloride as part of the anti-TB treatment, what needs to be checked? (2)
- Renal function
2. Visual acuity
Which anti-TB drug causes peripheral neuropathy?
Isoniazid
Why is pyridoxine hydrochloride added to isoniazid?
Reduces the risk of polyneuropathy
Which anti-TB drug can reduce the effectiveness of hormonal contraceptives?
Rifampicin
What foods should patients taking isoniazid avoid?
Tyramine-rich foods (e.g. mature cheeses, salami, pickled herring, Marmite, meat or yeast extract or fermented soya bean, some beers, lagers or wines)
The combination causes - tachycardia, palpitation, hypotension, flushing, headache, dizziness, sweating
What should be checked prior to a patient starting isoniazid to treat TB?
- Renal function
2. Hepatic function
What risk factors increase the likelihood of a patient taking isoniazid to develop peripheral neuropathy? (6)
- Diabetes
- Alcohol dependence
- Chronic renal failure
- Pregnancy
- Malnutrition
- HIV infection
Which 3 anti-TB drugs can cause hepatotoxicity?
Rifampicin
Isoniazid
Pyrazinamide