Background: A small proportion of goldminers in South Africa resist tuberculin skin test (TST)/interferon-gamma release assay (IGRA) conversion despite high rates of HIV and prolonged exposure to TB. We conducted a study among HIV-infected goldminers to determine the: i) proportion who resisted TST/IGRA conversion and ii) epidemiological factors associated with resistance to TST/IGRA conversion.
Methods: We enrolled HIV-infected goldminers who were on antiretroviral treatment, aged 33-60 years, with ≥15 years' service, no prior or current TB, no silicosis, and with body mass index >18.5 kg/m2. TST/IGRA conversion was assessed at baseline, 6 months, and 12 months using TST and QuantiFERON-TB-Gold-Plus (QFT-Plus). Miners were considered resisters if they had a zero TST response and a negative QFT-Plus at all visits. Logistic regression was used to identify epidemiological factors associated with TST/IGRA conversion resistance.
Results: We enrolled 245 HIV-infected miners with median age of 48 years (interquartile-range [IQR]: 44-52 years) and median CD4 count, 506 cells/ µ L (IQR: 372-677 cells/ µ L). Overall, 98.4% (241) were males and 99.2% (243) were Black/African with a median time of 24 years (IQR: 18-29 years) in the workforce. Of those completing all follow-ups, 24.3% (50/206) resisted TST/IGRA conversion. Miners who had a history of taking isoniazid preventive therapy (IPT) (adjusted odds ratio (aOR) 2.34; 95% confidence interval (CI): 1.14-4.80; p = 0.020) were more likely to resist TST/IGRA conversion. However, those from Mozambique (aOR 0.16; 95% CI: 0.04-0.71; p = 0.016) and those who had a CD4 count ≥500 cells/ µ L (aOR 0.46; 95% CI: 0.23-0.92; p = 0.028) were less likely to resist TST/IGRA conversion.
Conclusion: Similar to previous longitudinal cohort studies, we found a small proportion of HIV-infected goldminers who resisted TST/IGRA conversion. This was positively associated with prior IPT, but negatively associated with lower CD4 count and being from Mozambique. However, mechanisms underlying TST/IGRA conversion resistance are not well understood.
Copyright: © 2025 Ntshiqa et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.