Conference Abstract | Volume 9 (ConfPro8): Abstract 55 | Published: 08 Oct 2026
Hassan Adam Murtala1,&, Kasimu Mamuda2,3, Ibrahim Yusuf Ibrahim1, Aisha Adam Abdullahi1, Dalhatu Abdullahi Aminu3, Muhammad Adamu Abbas4,5, Abubakar Labaran Yusuf 6,7, Jordi Bertran Torrelles8, Eknath Naik9, Hamisu Mohammed Salihu1
1Department of Epidemiology and Population Health, Kano Independent Research Centre Trust (KIRCT), Kano, Nigeria, 2Infectious Disease Research Laboratory, Kano Independent Research Centre Trust (KIRCT), Kano, Nigeria, 3National Institute of Public Health and Infectious Diseases, Zaria, Nigeria, 4Office of the Director General, Kano State Center for Disease Control and Prevention (KNCDC), Kano, Nigeria, 5Department of Community Medicine, College of Health Sciences, Bayero University Kano, Kano, Nigeria, 6Office of the Commissioner of Health, Kano State Ministry of Health, Kano, Nigeria, 7Department of Medicine, Federal University Dutse, Jigawa, Nigeria, 8Division of Infectious Diseases, Department of Internal Medicine, College of Medicine, The Ohio State University, USA, 9University of South Florida, USA
&Corresponding author: Hassan Adam Murtala, Kano Independent Research Centre Trust, Email: Hassan.adam@kirct.com, ORCID:https://orcid.org/0009-0004-2827-4545
Received: 11 Mar 2026, Accepted: 30 Aug 2026, Published: 08 Oct 2026
Domain: Infectious Disease Epidemiology
Keywords: Tuberculosis, drug resistance, culture conversion, liquid culture, solid culture
©Hassan Adam Murtala et al. Journal of Interventional Epidemiology and Public Health (ISSN: 2664-2824). This is an Open Access article distributed under the terms of the Creative Commons Attribution International 4.0 License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Cite this article: Hassan Adam Murtala et al., Impact of differential culture contamination on monitoring treatment response among patients with drug-resistant tuberculosis in northern Nigeria. Journal of Interventional Epidemiology and Public Health. 2026;9(ConfPro8):55. https://doi.org/10.37432/JIEPH-CONFPRO8-0055
Culture conversion is the primary surrogate endpoint for treatment response in drug-resistant tuberculosis (DR-TB). Liquid (MGIT) and solid (Lowenstein-Jensen) cultures are both used for monitoring. However, whether they yield concordant conversion assessments in routine programmatic settings remains unknown in sub-Saharan Africa. We hypothesized that solid and liquid culture yield discordant conversion assessments in a routine programmatic DR-TB cohort and examined differential contamination between the methods.
We analyzed serial solid and liquid culture results at 12 time points (baseline to Month 18) in 130 consecutively enrolled DR-TB patients at the National Tuberculosis Reference Laboratory (NTBRL) in Zaria, Nigeria. Culture conversion was defined as two consecutive negative cultures, excluding contaminated and missing results. Kaplan-Meier estimates, log-rank tests, Cox proportional hazards regression, and Cohen’s kappa were used to compare conversion timing and agreement between methods.
Solid culture conversion was recorded in 61.5% (median 1 month), compared with 53.1% for liquid culture (median 4 months). Paired analysis showed that 16 patients converted on solid but not liquid, versus only 5 on liquid but not solid (p=0.03), and 64 dual converters. Liquid conversion lagged solid by a median of 1 month (p<0.001). Solid culture was contaminated more than three times as often as liquid culture (23.6% vs 7.1%). Additionally, solid contamination peaked in mid-treatment (37.0% versus 2.3% for liquid). Patients classified as converted by solid culture (40%) remained liquid-positive at or after their solid conversion timepoint. By Month 4, all solid cultures were negative, while the liquid culture still tested positive.
The apparent earlier conversion of solid culture is substantially an artefact of differential contamination. In high-contamination programmatic settings, solid-culture-based monitoring overestimates bacteriological clearance and may misclassify nearly half of converters. Liquid culture provides more reliable conversion monitoring in laboratories with high laboratory contamination.
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