32 HOW TO TREAT: LATENT TB INFECTION IN IMMUNO- COMPROMISED PATIENTS
32 HOW TO TREAT: LATENT TB INFECTION IN IMMUNO- COMPROMISED PATIENTS
20 MARCH 2026 ausdoc. com. au
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Figure 10. Indications for referral to an infectious diseases specialist.
disease. Quang is on multiple medications, including warfarin.
The GP decides to screen for LTBI and performs a QuantiFERON, which comes back positive. Quang is at risk as he was born and grew up in Vietnam, immigrating at the age of 30. He has no known contacts with active TB, and his chest X-ray demonstrates some scattered calcification in the right hilum. The combination of an
1. Which THREE statements are correct? a A significant proportion of the Australian population is immunocompromised and requires screening and / or treatment for latent TB infection( LTBI). b Patients with LTBI are at risk of progressing to active TB during the course of their lifetime. c In most patients, the host immune response cannot control TB. d Screening for LTBI may not be comprehensive in immunocompromised patients.
2. Which THREE are epidemiological risk factors for LTBI? a Born or resided in a TBendemic country. b Exposure to contact with active pulmonary TB. c Travel for six months or more outside of Australia. d Australians born before 1950.
3. Which THREE groups of patients are regarded as highly immunosuppressed? a HIV patients. b Patients on dialysis. epidemiological risk factor and a positive QuantiFERON makes it likely that he has LTBI. There are no symptoms or signs— either respiratory or constitutional— to suggest active TB.
The risk of TB reactivation over Quang’ s lifetime is about 2-3 %. The risk of hepatotoxicity or another serious adverse events is approximately 2-5 % using the TST calculator. 28 In addition, he has liver disease and is
How to Treat Quiz.
c Patients with a haematological malignancy. d Patients with primary immunodeficiency.
4. Which THREE methods are used for the diagnostic screening of LTBI? a Epidemiological. b Microbiological. c Radiological. d Immunological.
5. Which of the following statements regarding screening for LTBI are correct? a It is optimal to perform screening once the patient is on immunosuppressive medication. b In immunocompromised patients, it can be clinically difficult to exclude active TB. c Interferon-gamma release assay( IGRA) testing may be indeterminate. d IGRA testing requires one visit with a venepuncture. taking medications that will interact if rifampicin were used.
In light of this, the author would not offer Quang LTBI preventive treatment. The author recommends providing education about the symptoms and signs of active TB. It is also appropriate to contact his haematologist and advise that, although Quang has LTBI and this may reactivate, he will be managed with
LATENT TB INFECTION IN IMMUNOCOMPROMISED PATIENTS
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6. Which of the following statements regarding the risk of LTBI reactivation are correct? a Immunocompromised patients with LTBI have approximately a 5 % lifetime risk of reactivation. b Risk is dependent on the degree of immunosuppression and how recently M. tuberculosis was acquired. c Abnormalities seen on chest X-ray can inform the risk of reactivation. d Patients receiving biologic agents are at excess risk of reactivation.
7. Which are side effects of rifampicin? a Orange discolouration of urine, tears, saliva, semen, contact lenses. b Rash / hypersensitivity. c Peripheral neuropathy. d Thrombocytopenia.
8. Which of the following are part of the surveillance
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CONCLUSION
GPs have a key role in screening for LTBI in immunocompromised patients, who are at increased risk of reactivation of LTBI compared with immunocompetent patients. However, this risk varies depending on the underlying immunocompromising
and follow-up of LTBI in the immunocompromised? a Advise patients to wait at least four hours between taking their LTBI medication and drinking alcohol. b Regular LFTs, FBC and EUC. c Patient education about adherence. d Surveillance for active TB.
9. Which statements regarding follow-up after LTBI treatment completion are correct? a The IGRA and tuberculin skin test( TST) may remain positive lifelong. b There is no test to confirm successful completion of preventive treatment. c Repeat the IGRA and TST to confirm cure. d Order a repeat chest X-ray to confirm cure.
10. Which are indications for referral to an infectious diseases specialist? a Patients in whom active TB cannot be confidently excluded. b Patients on any medication. c Patients with an indeterminate test for LTBI. d Patient with liver disease. condition. Identifying patients with LTBI is key to preventing episodes of active TB. These patients often slip through the cracks when attending different specialists, and GPs play a pivotal role in ensuring this important screening does not get missed.
Screening for LTBI in immunocompromised patients can be problematic because of substantial rates of false-negative and indeterminate results.
Once LTBI is diagnosed, GPs will need to decide whether preventive treatment should be started. This decision is largely based on a balance between the risk of reactivation taken alongside the risk of side effects( hepatotoxicity) of isoniazid or rifampicin. The timing of initiation of LTBI therapy also requires some consideration, and this is done in collaboration with the team managing the immunosuppression.
There is no great urgency to start LTBI treatment in most patients. In certain circumstances, referral to an infectious diseases physician may be helpful.
Patient education and follow-up constitute a key part of LTBI preventive therapy.
RESOURCES
• Centers for Disease Control and Prevention: latent TB infection resources bit. ly / 3KiTdhi
• WHO— Global TB Report bit. ly / 3Kem32s
— Countries where TB is endemic bit. ly / 3UWikvy
— WHO global lists of high-burden countries for TB, TB / HIV and multidrug / rifampicin-resistant TB, 2021 – 2025 bit. ly / 3wQqMEv
• The Online TST / IGRA Interpreter tstin3d. com / en / calc. html
References Available on request from howtotreat @ adg. com. au