Abstract

Youssef Bighouab*, Hamza Bougoun, Rime Messaoudi, Bernoussi Taha, Benouda Amina

ABSTRACT

Provide on a separate page an abstract of not more than 150-250 words. Background: The control of Mycobacterium tuberculosis infection relies on the complementarity of microbiological and immunological tools. This study evaluates the diagnostic correlation between the multiplex PCR GeneXpert MTB/RIF and the QuantiFERON-TB Gold Plus (QFT-Plus) assay in a hospital setting. Methods: A retrospective, analytical, and observational study was conducted at the microbiology laboratory of Cheikh Zaid Hospital in Rabat over a 6-year period (2021–2026). The concordance analysis included a cohort of 43 patients who underwent simultaneous testing with a positive QFT-Plus and a GeneXpert MTB/RIF assay. Results: The overall mean age was 50.2 years with a sex ratio of 0.95, and 83.8% of the tests were performed on respiratory specimens. The analytical cross-tabulation highlighted. ? 21% concordance (QFT+ / PCR+): Indicating active pulmonary tuberculosis, confirmed 100% on respiratory specimens. ? 79% discordance (QFT+ / PCR-): Reflecting a predominance of latent tuberculosis infections (LTBI) in our endemic context, primarily screened prior to immunosuppression. In-depth analysis of the bacilliferous subgroup (QFT+ / PCR+) revealed: ? An immunological alert signature: A quantitative hypersecretion of interferon-gamma (≥ 4 IU/mL) and a biomarker inversion (TB2 > TB1), translating the activation of CD8+ cytotoxic T lymphocytes. ? A demographic shift: A clear rejuvenation (mean age of 36.3 years; 44.4% aged 20–29 years) and a strong masculinization (sex ratio of 2). Furthermore, no positive first-line PCR was subsequently followed by a QFT-Plus test. Conclusion: These two tests are strictly complementary. The discovery of a high-risk QFT-Plus profile (≥ 4 IU/mL and TB2 > TB1) must immediately raise suspicion of an evolving lesion and trigger a GeneXpert test. Maximum diagnostic vigilance is required for respiratory specimens in young male subjects, as this population is at the highest risk for contagious and cavitary tuberculosis.