Abstract:

Objective: To characterize the antimicrobial resistance to 2 kinds of quinolones and the related genes in
21 Salmonella hadar isolates obtained from poultry and meat samples from some farmer’s markets in Ürümqi for the purpose
of getting a better understanding of the pathways of generation and transmission of antimicrobial resistance and consequently
ensuring food safety. Methods: The drug sensitivity of Salmonella hadar was evaluated by agar dilution method. In addition,
PCR and gene sequencing were used to detect the presence of mutations in the quinolone resistance-determining region
(QRDR) and plasmid-mediated quinolone resistance genes. Results: The resistance rates of these 21 Salmonella hadar
isolates were 100% to nalidixic acid and they were sensitive to ciprofloxacin. The plasmid-mediated quinolone resistance
genes including qnrB (52.3%), qnrA (4.76%), and qnrS (4.76%) were identified. The 21 Salmonella hadar isolates had
mutations in the gyrA and parC genes at the same time. Among 21 Salmonella hadar isolates, the common mutations
appeared at Ser83Phe and Thr57Ser in the gyrA and parC genes, respectively. Conclusion: There should be concerns about
the serious situation of antimicrobial resistance in Salmonella hadar isolates from poultry and meat in Ürümqi. In addition,
the quinolone resistance-determining region (QRDR) mutations and the plasmid-mediated quinolone resistance genes may
affect the antimicrobial resistance of Salmonella hadar.

Key words: Salmonella, quinolone drugs, drug resistance, polymerase chain reaction (PCR), drug resistance gene