HIV-associated TB — DTM&H MCQ

Correct answer: D — Start TB treatment, then start ART within 2 weeks if tolerated

The correct answer is D, start TB treatment, then start ART within 2 weeks if tolerated. In HIV positive patients with active TB and a CD4 count below 50 cells/microlitre, sequencing matters: TB treatment must be started first to reduce the mycobacterial burden and the risk of immune reconstitution inflammatory syndrome (IRIS), followed by rapid ART initiation. This patient has no meningitis and drug-susceptible disease, so the standard rule applies rather than the meningitis exception, where early ART increases severe adverse events and death. UK guidance mirrors WHO practice: very low CD4 counts make untreated HIV the dominant mortality risk, so ART is escalated to within 2 weeks rather than the usual 8 to 12 weeks used for higher CD4 counts, since trial data show this reduces AIDS related mortality without an unacceptable rise in IRIS when meningitis is excluded. Why the other options are wrong: B. Treat TB with rifampicin monotherapy: TB treatment always requires a multidrug regimen (rifampicin, isoniazid, pyrazinamide, ethambutol); monotherapy rapidly selects for rifampicin resistant organisms and is never appropriate. A. Delay ART until completion of TB treatment: with CD4 less than 50, deferring ART for the full 6 months of TB therapy significantly increases mortality from HIV related opportunistic disease; only TB meningitis justifies prolonged deferral. E. Use isoniazid preventive therapy instead of TB treatment: this patient has confirmed active, smear-positive disease, not latent infection, so preventive monotherapy is inappropriate and would allow ongoing transmission and resistance development. C. Start ART immediately before TB medication: initiating ART first, ahead of anti-TB therapy, in a patient with a very high burden of untreated active TB and profound immunosuppression markedly raises the risk of severe unmasking IRIS; TB treatment must lead. Key point: In HIV-TB coinfection with CD4 under 50 and no meningitis, start TB treatment first then ART within 2 weeks; only TB meningitis mandates a delayed ART start.

Reference: BHIVA Guidelines for the Treatment of TB/HIV Coinfection 2018 (2024 update): recommend ART within 2 weeks of TB treatment start for CD4 counts below 50 cells/mm3, except in TB meningitis where early ART is not recommended. https://www.bhiva.org/wp-content/uploads/2024/10/BHIVA-TB-guidelines.pdf