Introduction. Salmonella 1,4, [5],12:i:- strains with different antimicrobial resistance profiles have been associated with foodborne disease outbreaks in several countries. In Brazil, S. 1,4, [5],12:i:- was identified as one of the most prevalent serovars in São Paulo State during 2004–2020. Gap Statement. However, few studies have characterized this serovar in Brazil. Aim. This study aimed to determine the antimicrobial resistance profiles of S. 1,4, [5],12:i:- strains isolated from different sources in Southeast Brazil and compare their genetic diversity. Methodology. We analysed 113 S. 1,4, [5],12:i:- strains isolated from humans (n=99), animals (n=7), food (n=5) and the environment (n=2) between 1983 and 2020. Susceptibility testing against 13 antimicrobials was performed using the disc diffusion method for all the strains. Plasmid resistance genes and mutations in the quinolone resistance-determining regions were identified in phenotypically fluoroquinolone-resistant strains. Molecular typing was performed using enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) for all strains and multilocus sequence typing (MLST) for 40 selected strains. Results. Of the 113 strains, 54.87 % were resistant to at least one antimicrobial. The highest resistance rates were observed against ampicillin (51.33 %), nalidixic acid (39.82 %) and tetracycline (38.05 %). Additionally, 39 (34.51 %) strains were classified as multidrug-resistant (MDR). Nine fluoroquinolone-resistant strains exhibited the gyrA mutation (Ser96→Tyr96) and contained the qnrB gene. The 113 strains were grouped into two clusters using ERIC-PCR, and most of strains were present in one cluster, with a genetic similarity of ≥80 %. Finally, 40 strains were typed as ST19 using MLST. Conclusion. The prevalence of MDR strains is alarming because antimicrobial treatment against these strains may lead to therapeutic failure. Furthermore, the ERIC-PCR and MLST results suggested that most strains belonged to one main cluster. Thus, a prevalent subtype of Salmonella 1,4, [5],12:i:- strains has probably been circulating among different sources in São Paulo, Brazil, over decades.

中文翻译：

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1983 年至 2020 年间，来自巴西的高水平多重耐药分离株遗传相似的沙门氏菌 1,4, [5],12:I:-

介绍。 沙门氏菌1,4, [5],12:i:- 具有不同抗菌药物耐药性的菌株与多个国家的食源性疾病暴发有关。在巴西，S . 1,4, [5],12:i:- 被确定为 2004 年至 2020 年圣保罗州最流行的血清型之一。差距声明。然而，很少有研究描述巴西这种血清型的特征。目的。本研究旨在确定沙门氏菌的抗菌耐药性概况。1,4, [5],12:i:- 从巴西东南部不同来源分离的菌株并比较其遗传多样性。方法。我们分析了 113  S。1,4, [5],12:i:- 1983 年至 2020 年间从人类 ( n = 99)、动物 ( n = 7)、食物 ( n = 5) 和环境 ( n = 2) 中分离出的菌株。使用纸片扩散法对所有菌株进行了针对 13 种抗菌药物的测试。在表型氟喹诺酮耐药菌株中鉴定出质粒耐药基因和喹诺酮耐药决定区的突变。使用肠细菌重复基因间一致性 PCR (ERIC-PCR) 对所有菌株进行分子分型，并使用多位点序列分型 (MLST) 对 40 个选定菌株进行分子分型。结果。在 113 株菌株中，54.87% 对至少一种抗菌药物具有耐药性。耐药率最高的是氨苄青霉素（51.33%）、萘啶酸（39.82%）和四环素（38.05%）。此外，39 株（34.51%）菌株被归类为多重耐药（MDR）菌株。9 株氟喹诺酮耐药菌株表现出gyrA突变（Ser96→Tyr96）并含有qnrB基因。ERIC-PCR将113株菌株分为两簇，大部分菌株集中在一簇，遗传相似度≥80%。最后，使用 MLST 将 40 株菌株定型为 ST19。结论。耐多药菌株的流行令人震惊，因为针对这些菌株的抗菌治疗可能会导致治疗失败。此外，ERIC-PCR 和 MLST 结果表明大多数菌株属于一个主簇。因此，沙门氏菌1,4, [5],12:i:- 菌株的流行亚型可能已在巴西圣保罗的不同来源之间传播了数十年。