Abstract

Tuberculosis (TB), caused by Mycobacterium tuberculosis, remains a major public health challenge in Nigeria, particularly with the emergence of drug-resistant strains. Rapid and accurate laboratory diagnosis is critical for effective disease control and patient management. This study aimed to evaluate Ziehl-Neelsen (ZN) smear microscopy, GeneXpert Ultra assay, and culture on Lowenstein-Jensen (LJ) medium for the detection of M. tuberculosis. A total of 150 sputum specimens were collected from presumptive TB patients between July 2024 and May 2025 across six states in the South-South geopolitical zone of Nigeria. All samples were processed using standard biosafety measures and laboratory protocols in a reference laboratory in Rivers State. The overall TB prevalence based on acid-fast bacilli detection was 69.3%. The GeneXpert MTB Ultra assay detected M. tuberculosis in 89.3% of samples. Culture on LJ medium yielded growth in 47.3% of samples, with NTM detection rate of 6.8% and a contamination rate of 8.5%. Genexpert MTB Ultra demonstrated a high positivity of 80.7% almost similar to the results provided by the Zeihl-Neelsen. LJ culture, had significant issues with contamination (8.5%), resulting in a 47.3% positivity rate. The findings highlight the complementary roles of microscopy, molecular, and culture-based diagnostic techniques in TB detection. Integrating rapid molecular diagnostics with conventional methods is essential to improve diagnostic accuracy and strengthen TB control efforts in high-burden settings.