Non-typhoidal salmonellosis remains a pressing public health problem worldwide. Quinolones, particularly fluoroquinolones, are widely used to treat various infections, including non-typhoidal salmonellosis, which can be a serious illness. The emergence of fluoroquinolone-resistant Salmonella has resulted in treatment failure and high mortality rates. In this study, we estimated the presence of plasmid-mediated quinolone resistance (PMQR) genes in Salmonella enterica isolated from human salmonellosis patients in South Korea from 2016 to 2019. We evaluated the association of these genes with fluoroquinolone susceptibility. Antimicrobial susceptibility tests for Salmonella isolates were performed using the Vitek II system, and the minimum inhibitory concentrations (MIC) of ciprofloxacin and levofloxacin were determined using the E-test method. Plasmid-mediated quinolone resistance (PMQR) genes were detected by PCR amplification and quinolone resistance-determining regions (QRDRs) of the gyrA and parC genes were analyzed following Sanger sequencing of the PCR products. Thirty-four Salmonella strains with reduced susceptibility to fluoroquinolones (ciprofloxacin MIC ≥ 0.125 µg/mL and levofloxacin MIC ≥ 0.25 µg/mL) were selected from 208 human clinical Salmonella isolates. Among them, 22 Salmonella strains harbored one PMQR gene (qnrA, qnrB, or qnrS), and three Salmonella strains carried two PMQR genes (qnrS and aac(6′)-Ib-cr or qnrA and qnrB). qnrS was the most common PMQR gene. Serotyping revealed that Salmonella 4,[5]12:i:- (32.4%, 11/34) and Salmonella Typhimurium (29.4%, 10/34) were the two most predominant serovars, and Multi-locus sequence typing (MLST) showed that ST19 and ST34 were the most frequent sequence types. In conclusion, qnr gene-positive Salmonella 4,[5],12:i:- and Salmonella Typhimurium were the main serovars responsible for reduced susceptibility to fluoroquinolones. Therefore, our findings suggest that PMQR-positive Salmonella strains, which can be isolated from various samples including human, food, and the environment, should be carefully monitored.

中文翻译：

---

2016 年至 2019 年在韩国京畿道人类沙门氏菌病中分离的氟喹诺酮类药物敏感性降低的非伤寒沙门氏菌菌株中存在质粒介导的喹诺酮抗性 (PMQR) 基因

非伤寒沙门氏菌病仍然是全球紧迫的公共卫生问题。喹诺酮类，尤其是氟喹诺酮类，被广泛用于治疗各种感染，包括非伤寒沙门氏菌病，这可能是一种严重的疾病。耐氟喹诺酮类沙门氏菌的出现导致治疗失败和高死亡率。在这项研究中，我们估计了 2016 年至 2019 年从韩国人类沙门氏菌病患者中分离的肠道沙门氏菌中质粒介导的喹诺酮抗性 (PMQR) 基因的存在。我们评估了这些基因与氟喹诺酮敏感性的关联。使用 Vitek II 系统进行沙门氏菌分离株的抗菌药物敏感性试验，并使用 E-test 方法确定环丙沙星和左氧氟沙星的最低抑菌浓度 (MIC)。通过PCR扩增检测质粒介导的喹诺酮抗性（PMQR）基因，并在PCR产物的桑格测序后分析gyrA和parC基因的喹诺酮抗性决定区（QRDR）。34 株对氟喹诺酮类药物敏感性降低的沙门氏菌菌株（环丙沙星 MIC ≥ 0.125 µg/mL 和左氧氟沙星 MIC ≥ 0.25 µg/mL）从 208 株人类临床沙门氏菌分离株中选出。其中，22株沙门氏菌携带一个PMQR基因（qnrA、qnrB或qnrS），3株沙门氏菌携带两个PMQR基因（qnrS和aac(6')-Ib-cr或qnrA和qnrB）。qnrS 是最常见的 PMQR 基因。血清分型显示沙门氏菌 4,[5]12:i:- (32.4%, 11/34) 和鼠伤寒沙门氏菌 (29.4%, 10/34) 是两种最主要的血清型，多位点序列分型 (MLST) 显示 ST19 和 ST34 是最常见的序列类型。总之，qnr 基因阳性沙门氏菌 4,[5],12:i:- 和鼠伤寒沙门氏菌是导致对氟喹诺酮类药物敏感性降低的主要血清型。因此，我们的研究结果表明，应仔细监测可从包括人类、食物和环境在内的各种样本中分离出的 PMQR 阳性沙门氏菌菌株。