Clinical, radiographic and microbiological manifestations of newly diagnosed pulmonary tuberculosis across CD4 strata in adults with advanced HIV disease: a real-world cross-sectional study in southern Vietnam

Background In advanced HIV disease, pulmonary tuberculosis (PTB) presents atypically and overlaps clinically, radiographically and microbiologically with Pneumocystis jirovecii pneumonia and bacterial infection. We describe these three axes across CD4 strata in adults with HIV-associated PTB. Methods Cross-sectional study of adults with HIV and microbiologically confirmed PTB at a tertiary referral hospital for tuberculosis and lung diseases in southern Vietnam (December 2022–September 2023). Chest radiography, sputum smear, Xpert MTB/RIF, culture and P. jirovecii microscopy were assessed across CD4 strata (Cochran–Armitage trend test; paired Xpert vs. smear, exact McNemar). Results CD4 was very low (median 40.5 cells/µL); most were ART-naïve and newly HIV-diagnosed. Radiographic patterns varied across CD4 strata: cavitation, consolidation and large nodules were more frequent in the highest than in the lowest CD4 stratum (100% vs. 3.8%, 88.9% vs. 30.8%, and 66.7% vs. 9.6%, respectively), whereas ground-glass opacity (GGO) was more frequent in the lowest stratum (50.0% vs. 0%); all four radiographic trends remained significant after correction (q ≤ 0.025). GGO also showed an unadjusted association with P. jirovecii positivity (odds ratio 5.67); among patients with CD4 ≥ 200 cells/µL, only four of nine were tested for P. jirovecii , and none was positive. At least one additional pulmonary organism was documented in 28/92 patients (30.4%). Smear positivity was 63.3% versus 91.1% for Xpert MTB/RIF (McNemar p < 0.0001), without a significant ordered trend for either test. Exploratory ROC analysis of absolute lymphocyte count showed an AUC of 0.89 (95% CI 0.79–0.96) for discriminating CD4 < 200 cells/µL. Conclusions Across CD4 strata, the manifestations of HIV-associated PTB varied: as CD4 fell, the radiograph shifted from cavitary and consolidative disease toward atypical, ground-glass-predominant patterns. Xpert positivity was higher than smear positivity across CD4 strata, with no significant ordered trend observed for either test. Additional pulmonary organisms were documented in a substantial proportion of patients. ALC may provide a supportive indicator of advanced immunosuppression when CD4 testing is unavailable but should not substitute for direct CD4 measurement. These descriptive, single-centre findings are hypothesis-generating and require prospective confirmation.