Genotyping and quinolone resistance analysis of multi-drug resistant tuberculosis strains in Ningbo, China

Objective To identify the Beijing family strains of multi drug-resistant tuberculosis (MDR-TB) and study the relationship between genotypes and quinolone resistance. Methods A total of 106 MDR isolates selected in the first drug resistance survey in Ningbo between 2014 and 2016 were used for the genotyping of Beijing family strain with RD105 deletion-targeted multiplex PCR. The conventional drug susceptibility test was used to detect the drug-resistant profiles against 3 quinolone antibiotics (levofloxacin, ofloxacin and moxifloxacin).Results Out of the 106 MDR-TB isolates, 83 belonged to Beijing family (78.3%), the remaining 23 isolates didn't belong to Beijing family (21.7%). There were 28 strains which were resistant to quinolone in 83 Beijing family MDR-TB strains (33.7%) and 6 strains which resistant to quinolone in 23 non-Beijing family MDR-TB strains (26.1%)(2=0.483, P0.05).Conclusion Beijing family MDR-TB strains were predominant in Ningbo, and Beijing genotype exhibited no association with quinolone resistance.