Strengthening Mycobacterial Culture and Identification Capacity through a Multi-Year Proficiency Testing Program in a Regional TB Laboratory Network

Introduction National TB Reference Laboratories, supported by the WHO Supranational Reference Laboratory Network (SRL), are central to TB diagnosis and quality assurance globally. Currently, low income settings are challenged with access to external quality assurance (EQA) programs. To assess the feasibility and performance, SRL-Uganda developed and implemented a multi-year ISO/IEC 17043:2023-aligned Mycobacterial culture and identification proficiency testing (PT) scheme to strengthen quality-assured culture and identification across regional laboratory networks Methods Mycobacterial culture proficiency testing materials were prepared at SRL-Uganda using well-characterized M. tuberculosis (H37Rv) and non-tuberculous mycobacteria reference strains under BSL-3 conditions. Materials were quality-checked, diluted, and assessed for stability over 21 days using Lowenstein–Jensen (LJ) medium and BACTEC MGIT 960 system. A pilot PT round in Uganda (2021) preceded three annual PT rounds distributed to 32 laboratories across 21 sub-Saharan African countries, with standardized scoring, consensus analysis, and performance classification aligned to ISO/IEC 17043:2023. Results The prepared mycobacterial culture and identification proficiency materials are stable up to 21 days at ambient temperature. Across three proficiency testing rounds, overall laboratory performance improved substantially, reaching 96.2% satisfactory results in the final round. Proficiency testing performance varied across rounds, declining in 2022 Round 2 but improving markedly by 2023, when over 96% of laboratories achieved satisfactory performance (≥ 80%), reflecting strengthened laboratory capacity over time. Conclusion Our findings demonstrate the feasibility of locally produced, stable PT materials and highlight the effectiveness of structured EQA in strengthening TB diagnostic capacity in resource-limited, high-burden settings.