Table_5_Invasive non-typhoidal Salmonella from stool samples of healthy human carriers are genetically similar to blood culture isolates: a report from the Democratic Republic of the Congo.DOCX

Invasive non-typhoidal Salmonella (iNTS) (serotypes Typhimurium and Enteritidis) are major causes of bloodstream infections in sub-Saharan Africa, but their reservoir is unknown. Aiming to demonstrate human carriers as a reservoir, we assessed an iNTS disease endemic rural community (Kikonka health area, Democratic Republic of the Congo) for intestinal carriage of iNTS. After a census, healthy subjects from randomly selected households provided three successive stool samples for Salmonella culture. We next compared the stool isolates for genetic relatedness with time and health area-matched blood culture isolates obtained from hospitalized patients by multiple locus variable-number tandem repeat analysis (MLVA) and performed whole genome sequencing (WGS) on a subset of stool and blood isolates. Among 2,354 eligible subjects, 2,234 (94.9%) consented and provided at least one stool sample, and 2,219 (94.3%) provided three stool samples. The cumulative proportion of Salmonella carriers after 3 days was 4.4% (n = 98). S. Typhimurium and Enteritidis were found in 26 and 3 carriers, respectively, representing 1.3% (29 out of 2,234) of participants living in 6.0% (26 out of 482) of households. MLVA types of all 26 S. Typhimurium stool isolates matched with the corresponding MLVA types of blood isolates. The MLVA type of one out of three Enteritidis stool isolates matched the single MLVA type of the five Enteritidis blood isolates. WGS analysis of S. Typhimurium (n = 20) and S. Enteritidis (n = 4) isolates revealed Typhimurium multilocus sequence type (ST)313 Lineage 2 and Enteritidis ST11 Central/Eastern African and Outlier clades and confirmed the MLVA clustering. More than three-quarters of Typhimurium isolates showed combined multidrug resistance, ceftriaxone resistance, and fluoroquinolone non-susceptibility. In conclusion, the present study demonstrated iNTS carriage among healthy community members, with stool isolates that were genetically similar to blood culture isolates obtained in patients from the same community. These findings contribute to the evidence of a human reservoir of iNTS.

侵袭性非伤寒沙门氏菌（Invasive non-typhoidal Salmonella, iNTS），血清型为鼠伤寒沙门氏菌（Typhimurium）和肠炎沙门氏菌（Enteritidis），是撒哈拉以南非洲地区血流感染的主要致病菌，但其贮存宿主目前尚不明确。本研究旨在证实人类携带者为其贮存宿主，我们针对位于刚果民主共和国的基孔卡（Kikonka）健康片区这一iNTS疾病流行的农村社区，开展了iNTS肠道携带状况的调查。在完成社区人口普查后，我们从随机抽取的家庭中招募健康受试者，连续采集3份粪便样本用于沙门氏菌培养。随后，我们采用多位点可变数目串联重复序列分析（multiple locus variable-number tandem repeat analysis, MLVA），对比粪便分离株与同期同健康片区住院患者的血培养分离株的遗传相关性；同时对部分粪便及血液分离株进行全基因组测序（whole genome sequencing, WGS）。在2354名符合纳入标准的受试者中，2234人（94.9%）签署了知情同意并提供至少1份粪便样本，其中2219人（94.3%）提供了3份粪便样本。3天后，沙门氏菌携带者的累积检出比例为4.4%（共98人）。其中26名携带者检出鼠伤寒沙门氏菌，3名检出肠炎沙门氏菌，占总受试者的1.3%（29/2234），分布于6.0%的受访家庭中（26/482）。所有26株鼠伤寒沙门氏菌粪便分离株的MLVA分型，均与对应血培养分离株的MLVA分型一致；3株肠炎沙门氏菌粪便分离株中，有1株的MLVA分型与5株肠炎沙门氏菌血培养分离株的单一MLVA分型相匹配。对20株鼠伤寒沙门氏菌及4株肠炎沙门氏菌分离株的全基因组测序分析显示，鼠伤寒沙门氏菌属于多位点序列分型（multilocus sequence type, ST）313谱系2，肠炎沙门氏菌则属于ST11中非/东非分支及域外进化支，上述结果验证了MLVA的聚类分析结果。超过四分之三的鼠伤寒沙门氏菌分离株表现出多重耐药、头孢曲松耐药及氟喹诺酮类不敏感的联合表型。综上，本研究证实了健康社区成员存在iNTS肠道携带现象，其粪便分离株与同一社区患者的血培养分离株具有遗传相似性。上述发现为iNTS存在人类贮存宿主提供了新的实证依据。