Validation of a liquid microarray technology combined with multiplex PCR for rapid detection of four quinolone-resistance genes in <i>Salmonella</i>

Salmonella has caused widespread foodborne disease risks in China. Studies suggest that plasmid-mediated quinolone resistance (PMQR) is the main route for the spread of Salmonella's drug resistance. To establish a method for rapid detection of the genus gene invA carried by foodborne Salmonella and four PMQR genes carried by drug-resistance strains based on multiplex PCR combined with liquid chip technology. The detection limits, sensitivity, specificity, and repeatability of the method were evaluated. Our findings revealed that in terms of detection sensitivity, this method can detect the invA and qnrS with a limit as low as 5 CFU/mL. The detection limits for aac(6')-Ib-cr, oqxA, and oqxB genes were 25 CFU/mL, 10 CFU/mL, and 10 CFU/mL, respectively. In terms of specificity, no positive signals were detected for the nontarget bacteria strains and the negative control. In the repeatability experiments, the coefficient of variation (CV) for all target gene detections was <5%. In the simulation sample verification, the concordance rate with the results of conventional PCR reached 100%. Therefore, this method can provide technical support for the detection of foodborne Salmonella and PMQR genes, as well as the monitoring of drug resistance.