Occurrence and Abundance of Antibiotic Resistance Genes in Chinese Traditional Pickles

With the widespread application and even misuse of antibiotics, antibiotic resistance genes (ARGs) are extensively present in various environments, from natural environment to fermented foods, posing emerging threat to public and environmental health. The real-time fluorescence quantitative PCR (qPCR) technique is commonly used to detect ARGs of environmental samples such as soil or water. In this study, eight types of pickles were collected from four regions of China and the existence of 13 resistance genes was assessed by qPCR. The results showed that a total of 11 resistance genes were detected in pickles, the blaTEM gene was detected in all samples, and the neo and cat genes were absent. The abundance of resistance genes varied, aada1 (1.09 × 10⁵ to 5.94 × 10⁶ copies/g), blaTEM (1.48 × 10⁵ to 2.2 × 10⁶ copies/g), ermc (1.01 × 10⁵ to 5.35 × 10⁵ copies/g), hyg (1.35 × 10⁵ to 1.93 × 10⁶ copies/g), aadd (4.46 × 10⁵ to 1.60 × 10⁶ copies/g), nat1 (1.04 × 10⁵ to 5.04 × 10⁵ copies/g), nptII (2.17 × 10⁴ to 1.69 × 10⁵ copies/g), sul1 (2.01 × 10⁵ to 4.60 × 10⁵ copies/g), tetl (1.23 × 10⁵ to 6.18 × 10⁵ copies/g), shble (1.68 × 10⁴ copies/g), and stra (4.8 × 10⁴ to 1.9 × 10⁵copies/g). We also discussed the specificity and sensitivity assessment of qPCR applied to ARGs analysis in pickles, verifying the feasibility and validity of the method. Bacteria were isolated and purified from pickles as well and their antimicrobial resistance was studied. This study is of great significance for the risk assessment of resistance genes in pickles. Effective and preventive solutions were proposed to reduce the spread of resistance genes and protect public dietary health.