Study on the prevalence of Beijing genotype Mycobacterium tuberculosis and its relationship with second-line anti-tuberculosis drug resistance

Abstract

Objective: To explore the prevalence risk factors of Beijing genotype Mycobacterium tuberculosis (MTB) in Beijing and its correlation with second-line anti tuberculosis drug resistance. Methods: A total of 1 140 clinical MTB positive strains were collected from various districts in Beijing, and the drug sensitivity was detected by proportion method. Beijing genotype and non Beijing genotype MTB were identified by the method of Spoligotyping. Using SPSS 22.0 statistical software, chi square test or Fisher exact probability test was used to analyze the experimental data. Results: Among 1 140 MTB clinical isolates, 941 (82.5%) were Beijing genotype MTB, 199 were non Beijing genotype MTB. There were 663 males (70.5%) in Beijing genotype and 124 males (62.3%) in non Beijing genotype strains. There were significant differences in the proportion of males between the two genotypes [P=0.021, OR (95% CI):1.442 (1.048-1.985)]. There were 441 floating population (46.9%) in Beijing genotype MTB and 78 floating population (39.2%) in non Beijing genotype MTB. There was a significant difference in the proportion of floating population between the two genotypes [P=0.048,OR (95%CI):1.368(1.001-1.869)]. There were 129 patients (13.7%) aged 65 or older in Beijing genotype MTB, 40 patients (20.1%) aged 65 or older in non Beijing genotype MTB. The difference was statistically significant [P=0.021, or (95% CI): 0.631 (0.426-0.936)]. The resistance drug rates of Levofloxacin (Lfx), Amikacin (Am), Capreomycin (Cm), Para-aminosalicylic (PAS) in Beijing genotypes were 5.5% (52/941), 1.3% (12/941), 3.2% (30/941) and 3.0% (28/941), respectively, and those of non Beijing genotypes were 10.6% (21/199), 8.5% (17/199, 12.6% (25/199) and 11.6% (23/199), the difference was statistically significant (all P<0.05). There were 58 (6.2%) multidrug-resistant (MDR) strains in Beijing genotype MTB and 19 (9.5%) multidrug-resistant strains in non Beijing genotype. There was no significant difference in the proportion of MDR strains between Beijing genotype and non Beijing genotype (P>0.05). Conclusions: Beijing genotype MTB is widespread in Beijing and has a higher proportion in male population and floating population. Compared with non Beijing genotype, Beijing genotype MTB has a lower resistance rate to Lfx, Am, Cm and PAS, and there is no significant difference in the proportion of MDR-TB patients between the two genotypes.