New HIV infection, ART already started, then cavitary tuberculosis
A 34-year-old man was diagnosed with HIV infection three weeks ago after a prolonged febrile illness. His CD4 count was 68 cells/µL and he was started on tenofovir, lamivudine and dolutegravir. He now returns with a three-week history of productive cough, night sweats and 4 kg of weight loss. The chest radiograph shows right upper lobe consolidation with cavitation. Two sputum samples are smear-negative for acid-fast bacilli, but Xpert MTB/RIF on the second sample is positive, with no rifampicin resistance. ALT is 40 U/L, creatinine 0.9 mg/dL and haemoglobin 9.6 g/dL. He reports good adherence to antiretroviral therapy and has no other opportunistic infection. The clinic stocks rifampicin, isoniazid, pyrazinamide and ethambutol as fixed-dose combinations and reviews patients weekly.
1. What is your treatment sequencing and regimen, and what drug interaction must be addressed immediately?
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Start standard anti-tuberculosis treatment now: two months of rifampicin, isoniazid, pyrazinamide and ethambutol, followed by four months of rifampicin and isoniazid, using fixed-dose combinations dosed by weight. Do not stop antiretroviral therapy. Starting tuberculosis treatment promptly matters because he has smear-negative but Xpert-confirmed, cavitary disease with systemic symptoms and a low CD4 count, and interrupting antiretroviral therapy risks rebound immunosuppression and resistance.
The interaction to address before the first dose is between rifampicin and dolutegravir. Rifampicin is a potent inducer of uridine glucuronosyltransferase and CYP3A4 and substantially lowers dolutegravir exposure. Increase dolutegravir to 50 mg twice daily for the duration of rifampicin treatment, then return to 50 mg once daily after rifampicin stops. Tenofovir and lamivudine need no dose change. Check whether he is on cotrimoxazole prophylaxis, which is indicated at a CD4 count below 200 cells/µL, and start it if not.
Baseline liver enzymes are normal, which is reassuring, but obtain a baseline and repeat them if symptoms develop, because both rifampicin and isoniazid are hepatotoxic and the presentation may overlap with drug-induced injury. Arrange adherence support and a treatment supporter, and screen household contacts.
2. What is the risk of immune reconstitution inflammatory syndrome here, and how would you recognise it?
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This man is at substantial risk of paradoxical tuberculosis-associated immune reconstitution inflammatory syndrome. He has a very low CD4 count, a high mycobacterial burden with cavitation, and antiretroviral therapy was started before tuberculosis treatment - the sequence that most strongly predisposes to paradoxical reactions, because immune recovery is already under way when antigen load is high.
Expect it typically 2–8 weeks after starting antituberculosis treatment, though it can occur later. Recognise it as a worsening or recurrent inflammatory illness in a patient who is otherwise responding: recurrent or worsening fever, enlarging or new lymph nodes, worsening cough or breathlessness, increasing radiographic infiltrates or new pleural effusion, and sometimes painful cutaneous lesions. He is also at risk of unmasking TB-IRIS for other organisms, but here the tuberculosis diagnosis is already established.
The critical step is to exclude the alternatives before labelling it IRIS: treatment failure from non-adherence, drug resistance (rifampicin susceptibility is known but isoniazid resistance is not excluded), a new opportunistic infection such as cryptococcal disease or Pneumocystis pneumonia, and drug toxicity. Send further sputum for culture and susceptibility, check adherence, and look for another infection. Do not stop antituberculosis drugs or antiretroviral therapy on the assumption of failure; doing so precipitates resistance and immunosuppression.
3. How would you manage IRIS once other causes are excluded, and what longer-term monitoring does he need?
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Management is graded by severity. For mild paradoxical reactions - low-grade fever, modest node enlargement, no compromise of a vital organ - continue both treatments unchanged, explain the cause to the patient, and use simple analgesia such as paracetamol or a short course of a non-steroidal anti-inflammatory drug if the kidneys allow.
For severe reactions, give corticosteroids: prednisolone at approximately 1–1.5 mg/kg/day, then taper over several weeks according to response. Severe means airway compromise from cervical adenopathy, hypoxia or worsening pulmonary infiltrates, significant pleural or pericardial effusion, central nervous system involvement, or severe systemic illness. Admit him for oxygen, drainage of significant effusions if needed, and close observation. Continue antituberculosis treatment and antiretroviral therapy throughout; stopping either to treat IRIS is the wrong move. If the reaction is life-threatening and refractory, involve a specialist in HIV medicine.
Longer-term monitoring: monthly weight and clinical review, liver enzymes if symptomatic, sputum at the end of the intensive phase, visual acuity for ethambutol, adherence and pill burden with twice-daily dolutegravir, viral load and CD4 count at the appropriate intervals, cotrimoxazole prophylaxis, and screening for other opportunistic infections and for household tuberculosis contacts. Prepare him for the fact that his symptoms may transiently worsen as his immune system recovers, so that he does not abandon treatment.