Emergence of the Beijing strain linked to multidrugresistant tuberculosis genotypes among baseline and follow-up strains in Eswatini
Keywords:
tuberculosis, multidrug-resistant tuberculosis, drug sensitivity testing, spoligotyping, lineages, genotypesAbstract
Background: The tuberculosis (TB) epidemic remains a major global health problem, particularly in Eswatini. Our study aimed to investigate the circulating genotypes in Eswatini and to determine genotype changes of susceptible Mycobacterium tuberculosis (M. tb) genotypes when they develop into multidrug-resistant tuberculosis (MDR-TB) genotypes during treatment.
Methods: Participants (n = 390) were prospectively enrolled from referral clinics and patients who met the inclusion criteria were included in the study. A total of 206 M. tb strains were detected at baseline and follow-up (at six months or the last positive sample from a treated patient) by GeneXpert® MTB/RIF assay (Cepheid, USA) and microscopy, respectively. The decontaminated specimens were processed on the BACTEC™ Mycobacteria Growth Indicator Tube (MGIT™) 960 Mycobacteria Culture System (Becton Dickinson, USA) for culture drug sensitivity testing (DST) at both baseline and follow-up. Spoligotyping was performed on both baseline and follow-up strains. The study results were analysed using the Statistical Package for the Social Sciences (SPSS) version 25 software and STATA.
Results: A total of 82.5% (170/206) of genotypes had valid spoligotyping patterns, with 4 lineages and 20 genotypes. The distribution of the lineages varied among the different regions in Eswatini. A high proportion of the Beijing genotype at 24.27% (50/206) and the S genotype at 16.50% (34/206) were detected. Furthermore, the Beijing genotype strain was predominantly found in followup genotypes from the Manzini region with 48.9% (23/47), which was significant. A significant proportion of follow-up specimens developed MDR-TB (p = 0.001), with the Beijing genotype being the major genotype in most follow-up specimens (p < 0.000).
Conclusion: In Eswatini, the Beijing genotype is associated with MDR-TB in follow-up specimens, which indicates community-wide transmission.
