Abstract:

Objective: To investigate the causes of recurrence in tuberculosis patients in Beijing and the genetic characteristics of their strains, aiming to provide a scientific basis for the effective prevention and treatment of recurrent tuberculosis patients. Methods: The RD105 gene deletion method and 15-locus variable number tandem repeat genotyping experiment (VNTR) were used to compare the genotypes of Mycobacterium tuberculosis (MTB) of the initial and recurrent episodes in pulmonary tuberculosis patients in Beijing from January 2017 to December 2019, to elucidate the etiology of recurrent tuberculosis. The final isolates from recurrent patients were selected to evaluate the discriminatory ability of the genotyping technology on MTB strains of Beijing. Furthermore, a phylogenetic analysis was conducted to investigate the genetic characteristics of MTB prevalent in recurrent patients, providing insights into the evolutionary relationships within the strains associated with recurrent tuberculosis cases in Beijing. Results: The proportion of endogenous reactivation among recurrent patients was 65.4% (51/78), while the proportion of exogenous reinfection was 34.6% (27/78). Among the 78 MTB isolates obtained from recurrent patients, 71 were Beijing genotype, and 7 were non-Beijing genotype. 78 strains exhibited 68 distinct genotypes. Within 2 clonal complex clusters, 13 isolates formed 4 clusters, while among 24 unique strains, 2 isolates formed 1 cluster, resulting in a clustering rate of 12.8%. The hunter-gaston discrimination index for all MTB strains across the 15 VNTR loci was 0.994. Conclusion: The primary cause of recurrent tuberculosis in Beijing was endogenous reactivation, with a relatively low clustering rate. The predominant strain was Beijing genotype, exhibiting a high degree of genetic diversity.

Key words: Recurrence, Mycobacterium tuberculosis, Genotype