A case report of complex co-infection with Talaromyces marneffei and Rhodococcus equi in a patient with AIDS

Co-infection with Talaromyces marneffei (TM) and Rhodococcus equi(R.equi) in HIV-positive patients is an extremely rare but life-threatening combination of opportunistic infections. We report a case of an HIV-infected patient with profound immunosuppression (CD4 + T cell count 72 cells/µL) who was initially misdiagnosed as pulmonary tuberculosis due to acid-fast positive cocci, but was subsequently confirmed by bone marrow culture, bronchoalveolar lavage fluid culture, and targeted next-generation sequencing (tNGS) to have co-infection with R. equi and TM. A 32-year-old male with AIDS (CD4 + T cell count 72 cells/µL) presented with two months of fever, cough, and progressive weight loss (9 kg). He was admitted on June 25, 2025, after initial misdiagnosis as pulmonary tuberculosis at a local hospital. Acid-fast positive cocci were observed in sputum smears on June 26. Bone marrow culture confirmed R. equi sepsis on June 27, and bronchoalveolar lavage fluid (BALF) culture and tNGS identified co-infection with R. equi and TM on June 29. The antimicrobial regimen was adjusted to levofloxacin, amikacin, and azithromycin for R. equi , and amphotericin B was initiated for TM. On June 30, ART was optimized to TDF/3TC/DTG. On July 1, oral candidiasis was diagnosed and treated with sodium bicarbonate mouthwash. On July 7, the patient developed septic shock (blood pressure 87/56 mmHg), requiring immediate resuscitation. By July 9, his condition stabilized, and he was discharged on oral itraconazole, levofloxacin, and antiviral therapy. The patient developed probable immune reconstitution inflammatory syndrome (IRIS) shortly after ART optimization, manifesting as septic shock. This case highlights that R. equi , due to its acid-fast positivity, is easily misdiagnosed as tuberculosis in HIV-positive patients. Definitive etiological diagnosis through bone marrow aspiration and bronchoscopy, combined with tNGS, is essential for distinguishing R. equi /TM co-infection from tuberculosis and enabling targeted combination therapy. Clinicians should maintain a high index of suspicion for opportunistic co-infections in advanced AIDS with atypical presentations.