Objective: To understand the serotype distribution, drug resistance and molecular characterization of invasive non-typhoid Salmonella (iNTS) in Guangdong Province from 2018 to 2022 and provide scientific evidence for the prevention and treatment of blood flow infection caused by Salmonella. Methods: Serological identification, antimicrobial susceptibility testing, multilocus sequence typing (MLST), and whole genome sequencing were performed on Salmonella isolated from blood and stool samples in Guangdong from 2018 to 2022. Simultaneously, annotated the sequencing results for drug resistance genes and virulence factors by a microbial gene annotation system. Results: The 136 iNTS strains were divided into 25 serotypes, and Salmonella enteritidis accounted for 38.24% (52/136). The OR of other iNTS serotypes were calculated with Salmonella typhimurium as the control. The OR values of Oreninburg, Rysson, and Pomona serotypes were the highest, which were 423.50, 352.92, and 211.75, respectively. The drug resistance rate of iNTS was 0.74%-66.91%, which was lower than that of non-iNTS (3.90%-77.21%). The main iNTS of drug resistance were ampicillin and tetracycline, with resistance rates of 66.91% (91/136) and 50.00% (68/136), respectively, while the resistance rates to ciprofloxacin (5.88%,8/136), ceftazidime (5.88%,8/136), gentamicin (5.13%,7/136) and cefoxitin (0.74%, 1/136) were relatively low. iNTS carried a variety of drug-resistance genes and virulence factors, but no standard virulence factor distribution has been found. MLST cluster analysis showed that iNTS was divided into 26 sequence types, and ST11 accounted for 38.24% (52/136). Conclusions: The iNTS strains in Guangdong were dominated by Salmonella enteritidis, of which three serotypes, Oreninburg, Rison, and Pomona, may be associated with a higher risk of invasive infection during 2018 to 2022. iNTS was sensitive to clinical first-line therapeutic drugs (cephalosporins and fluoroquinolones), with highly diverse sequences and clear phylogenetic branches. ST11 was the local dominant clone group.
目的： 了解2018-2022年广东省侵袭性非伤寒沙门菌（iNTS）的血清型分布、耐药性以及分子流行情况，为沙门菌侵袭性感染的防治提供科学依据。 方法： 对2018-2022年广东省分离自血液和粪便样本的沙门菌进行血清学鉴定、药敏试验、多位点序列分型（MLST）和全基因组测序。同时利用微生物基因注释系统对测序结果开展耐药基因与毒力因子注释。 结果： 136株iNTS分为25种血清型，肠炎沙门菌占38.24%（52/136）。以鼠伤寒变种沙门菌作为对照计算其余iNTS血清型的OR值，奥雷宁堡、里森和波摩那3种沙门菌血清型的OR值较高，分别为423.50、352.92和211.75。iNTS耐药率在0.74%~66.91%之间，普遍低于非iNTS株（3.90%~77.21%）。iNTS耐药以氨苄西林和四环素为主，耐药率分别为66.91%（91/136）和50.00%（68/136），而对环丙沙星（5.88%，8/136）、头孢他啶（5.88%，8/136）、庆大霉素（5.13%，7/136）和头孢西丁（0.74%，1/136）耐药率较低。iNTS携带多种耐药基因与毒力因子，但尚未发现共同毒力因子分布特征。MLST聚类分析显示，iNTS分为26种序列型别，ST11型占38.24%（52/136）。 结论： 2018-2022年广东省iNTS以肠炎沙门菌为主，其中奥雷宁堡、里森和波摩那3种血清型可能与更高的侵袭性感染风险有关。iNTS对临床一线治疗药物（头孢类和氟喹诺酮类抗生素）敏感，序列呈现高度多样性且具有明确的系统发育分支，以ST11型为本地优势克隆群。.