Pre-extensively drug-resistant tuberculosis among multidrug-resistant tuberculosis patients in Ethiopia: A laboratory-based surveillance study

•Patients with a history of previous TB have a high pre-XDR-TB•Second-line drug resistance mutations were most common in the gyrA gene.•Rapid DST is necessary to detect pre-XDR-TB and XDR-TB in Ethiopia. The rise of drug-resistant tuberculosis (DR-TB) has imposed a substantial challenge to the national tuberculosis (TB) control program. Understanding the epidemiology of pre-XDR-TB could help clinicians to adapt MDR-TB treatment regimens at an earlier possible time. This study aimed to assess second-line anti-TB drug resistance among MDR-TB patients using routine laboratory-based data in Ethiopia. A laboratory-based cross-sectional data were collected from the national TB reference laboratory and seven regional tuberculosis culture laboratories in Ethiopia from July 2019 to March 2022. Required data such as drug-susceptibility testing (DST) results and socio-demographics were collected on a structured checklist from laboratory registration books and electronic databases. Data were entered into a Microsoft Excel spreadsheet and analyzed by SPSS version 23. Descriptive statistic was performed to show the distribution and the magnitude of drug resistance. Second-line drugs (SLDs) susceptibility testing was performed for 644 MDR isolates, and 19 (3%) isolates were found to be pre-XDR-TB cases. Of the total MDR-TB isolates, 19 (3%) were resistant to at least one fluoroquinolone drug, while 11 (1.7%) were resistant to at least one second-line injectable drug. Of the 644 MDR-TB isolates 1.9% (5/261) pre-XDR were from new MDR-TB cases, while 3.7% (14/383) were from previously treated MDR-TB patients.. The most frequently identified mutations were in codon A90V (77.3%) of the gyrA gene and A1401G (45.5%) of the rrs gene based on MTBDRsl results. The overall prevalence of pre-XDR-TB in Ethiopia is considerable. The majority of SLD resistance mutations were gyrA gene at position A90V. Modern rapid DST is necessary to enable access to pre-XDR-TB and XDR-TB to support proper regimen administration for the patients.