TB Flashcards
When should new UK entrants be offered BCG vaccination?
If aged under 16
OR
Aged 16-35 and coming from Sub-Saharan Africa or a country with TB incidence >500 per 100,000 (High Risk)
What are the indications for Newborn BCG vaccination?
Born in an area with high incidence of TB
1 or more parents or grandparents who were born in a high risk country
What are the indications for BCG vaccination for contacts of people with active TB?
Negative Mantoux test (not prev exposed/infected)
No previous vaccination
Aged under 35 OR
Aged 36+ and a healthcare/laboratory worker with direct contact with patients or clinical materials
Which occupational groups are eligible for BCG vaccination? Is there an age cut off?
Vetinary/abbatoir workers who are in contact with animals known to be susceptible to TB
Prison staff working directly with prisoners
Staff of hostels for the homeless or housing refugees/asylum seekers
People going to live/work with people in a high incidence country for >3months
What is the Mantoux test and how is it used? Who should it be offered to? What constitutes a positive result?
Mantoux test (intradermal tuberculin injection with results assessed at - 2-3 days) should be offered to anyone aged 18 to 65 who is a close contact of someone with active pulmonary or laryngeal TB or to new healthcare workers.
Induration of >5mm is classed as positive (irrespective of BCG status)
Can also perform IGRA. If both IGRA and Mantoux positive and active TB excluded then treat for latent TB.
What are the advantages of using IGRA over Mantoux in diagnosing latent TB?
Less likely to give a false positive result
Results available quicker
Useful in under served groups as a single point of contact test
What is the appropriate screening for new healthcare workers (TB)?
If not from a high risk country AND no BCG then offer a MANTOUX test. If this is POSITIVE then offer an IGRA. If IGRA positive then assess for active TB and treat for latent TB if assessment negative.
If high risk country of origin and no BCG then offer mantoux
If from high prevalence place and direct contact with patients then offer IGRA directly. Even if negative, offer Rx for latent TB.
What are the treatment regimens for latent TB (assuming sensitive)?
3 months of rifampicin and isoniazid (with pyridoxine) if aged <35 and hepatotoxicity a concern
OR
6 months of isoniazid (+pyridoxine) if interactions with rifampicin are a concern
Offer HIV and Hep B/C testing prior to starting treatment.
What is the treatment regimen and duration for active TB?
2 months of rifampicin, isoniazid (+pyridoxine), pyrizinamide and ethambutol THEN
4 months of rifampicin and isoniazid (+pyridoxine)
Extend the total course to 12 months if suspected CNS involvement
If active TB is suspected, what testing should be performed on the sample? When should it be tested for MDR?
All TB samples should be tested for Rifampicin resistance. If previous treatment for TB (especially if poor adherence) then should test for MDR, if direct contact with a case of MDR or if from a country with >5% of newly diagnosed cases being MDR
What is the treatment regimen for Isoniazid-resistant TB?
Rifampicin, Ethambutol and pyrizinamide for 2 months
THEN
Rifampicin and ethambutol for a further 7 months (up to 10 months total)
What is the treatment for Pyrazinamide-resistant TB?
Rifampicin, isoniazide (+pyridoxine) and ethambutol for 2 months initial phase
Continue rifampicin and isoniazid for a further 7 months
What is the treatment for Ethambutol-resistant TB?
Rifampicin, Isoniazid (+pyridoxine) and pyrazinamide for initial 2 months
Rifampicin and isoniazid for a further 4 months
How should a person with MDR-TB be managed if they require hospital admission?
Should stay in a negative pressure room if MDR-TB suspected until non-resistance confirmed.
To remain in negative pressure room if confirmed MDR-TB until 3 consecutive negative smears at weekly intervals and ideally a negative culture.
When should communicable disease control be informed if a TB patient has travelled on a plane?
If the patient has confirmed SMEAR POSITIVE TB, the flight was WITHIN 3 months and the TB is confirmed MDR or the patient coughed frequently during the flight.
‘Inform and advise’ information should be given to those that were in close proximity.
How should TB drugs be restarted if suspected hepatotoxicity?
Rule out any other causes of acute liver reactions
Wait until AST or ALT levels fall below twice the upper limit of normal and bilirubin normalises & symptoms resolve
THEN
Sequentially reintroduce anti-TB drugs at FULL dose over NO MORE THAN 10 DAYS, starting with ethambutol and either isoniazid or rifampicin
How would you manage hepatotoxicity in a patient with severe/highly infectious TB?
At LEAST 2 anti-TB drugs with low hepatotoxicity such as ethambutol and streptomycin +/- fluoroquinolone (levofloxacin or moxifloxacin). Monitor in conjunction with a liver specialist
What testing is recommended for any smear positive TB samples? What are the recommended assays?
Any smear positive or sample with high clinical suspicion for TB should undergo MOLECULAR testing for rapid TB identification.
Xpert MTB or RIF Ultra are the recommended assays (British HIV association)
When should antiretroviral treatment be started if TB is diagnosed?
Within 4 weeks irrespective of CD4 count. If CD4 count <50 then it should be started within 2 WEEKS
However if suspected CNS TB then this should be delayed for up to 8 weeks.
What is the recommended ART in patients taking rifampicin-based TB therapy?
Efavirenz (standard dose) plus tenofovir disoproxil and emtricitabine as first line
If a patient requires Ritonavir-boosted ART, what change should be made to their TB regimen?
Switch Rifampicin to rifabutin
As per 2020, what was the incidence rate of TB in the UK?
7.3 per 100,000.
This was a decrease from the year before (8.4%)
Of the diagnoses, 2.9% had HIV co-infection
What effect does rifampicin have upon cytochrome p450 metabolised drugs?
Rifampicin increases the clearance of drugs metabolised by cytochrome p450 as it’s an enzyme inducer.
Can lead to lower therapeutic levels of drugs such as phenytoin
When should oseltamivir be started in influenza infection?
Within 48 hours of symptom onset
What is babesiosis and how is it treated?
It is a malaria-like illness caused by Ixodes scapularis (deer tick), so common from forested areas. Also known as ‘Texas fever’. Diagnosed on blood smear with TETRAD/RING pattern in the RBCs. Treat with atavaquone and a macrolide such as azithro/clarithromycin
OR clindamycin and a quinine
How is MDR TB defined?
TB that is resistant to both rifampicin and isoniazid
How is pre-XDR TB defined?
TB that is resistant to both rifampicin and isoniazid PLUS a fluoroquinolone
How is XDR TB defined?
TB resistant to rifampicin and isoniazid (MDR) PLUS a fluoroquinolone AND an additional first line treatment drug
What is the correct treatment for M.bovis infection?
Rifampicin, ethambutol and isoniazid for 2 MONTHS then Rifampicin and ethambutol for 7 MONTHS
M. Bovis is naturally resistant to pyrazinamide so treat as per pyrazinamide-resistant TB
When is adjunct treatment with corticosteroids recommended in the treatment of TB?
When there is either CNS or PERICARDIAL involvement
