TITLE:
Primary Drug-Resistant Mycobacterium Tuberculosis in Yaoundé, Cameroon: Microbiological and Molecular Characterization
AUTHORS:
Alexandra Emmanuelle Membangbi, Jean-Paul Assam Assam, Esther Del Florence Ndedi Moni, Elsa Nguiffo Makue, Andre Urbain Njiki-Bikoi, Sara Honorine Riwom, Jacky Njiki-Bikoï
KEYWORDS:
Line-Probe Assay, rpoB Mutations, katG Mutations, Molecular Epidemiology, Drug-Resistant Tuberculosis, Cameroon
JOURNAL NAME:
Open Journal of Medical Microbiology,
Vol.16 No.3,
September
17,
2026
ABSTRACT: Background: Drug-resistant tuberculosis threatens global TB control, yet molecular resistance patterns remain poorly characterized in Central Africa. We investigated the prevalence and molecular characteristics of primary drug resistance among newly diagnosed pulmonary TB patients in Yaoundé, Cameroon. Methods: We conducted a prospective study at Jamot Hospital, Yaoundé (March 2023-September 2025). Of 147 screened patients, 105 treatment-naïve, HIV-negative, smear-positive pulmonary TB patients aged ≥ 21 years residing within 50 km of Yaoundé were enrolled. MGIT liquid culture and GenoType® MTBDRplus line-probe assay were used to characterize resistance to rifampicin and isoniazid and to identify specific mutations in rpoB, katG, and inhA genes. Of 100 culture-positive isolates, 98 were successfully genotyped. Results: Among 98 genotyped isolates, 32.7% (32/98) exhibited drug resistance: 14.3% rifampicin mono-resistance, 11.2% isoniazid mono-resistance, and 7.1% MDR-TB, substantially exceeding national estimates (2.4%). Molecular characterization revealed a distinctive regional resistance profile: rpoB H526Y/D mutations predominated (76.2% of rifampicin-resistant isolates) over the globally common S531L (23.8%), while katG S315T accounted for 77.8% of isoniazid resistance. Among the 66 fully susceptible patients who completed standard 2HRZE/4HR therapy, 96.2% achieved sputum conversion by month 6; outcome data for resistant patients referred to MDR-TB programmes were not available within the study timeframe. The elevated mono-resistance rates warrant cautious interpretation, as undisclosed prior treatment cannot be entirely excluded. Conclusion: Yaoundé exhibits unexpectedly high primary drug resistance with a distinctive H526-predominant molecular signature. Whether this pattern reflects clonal transmission of specific lineages requires confirmation by whole-genome sequencing and strain typing, which are urgently needed. Universal molecular drug susceptibility testing at diagnosis is a priority. Findings are applicable to smear-positive, treatment-naïve adults ≥ 21 years near Yaoundé and should not be extrapolated to paediatric, smear-negative, or HIV-co-infected populations.