AUTHOR=Mbuyi-Kalonji Lisette , Hardy Liselotte , Mbuyamba Jules , Phoba Marie-France , Nkoji Gaëlle , Mattheus Wesley , Im Justin , Marks Florian , Jeon Hyon Jin , Jacobs Jan , Lunguya Octavie 

TITLE=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

JOURNAL=Frontiers in Microbiology

VOLUME=Volume 14 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1282894

DOI=10.3389/fmicb.2023.1282894

ISSN=1664-302X

ABSTRACT=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 3 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; 2,219 (94.3%) provided 3 stool samples. 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% (29/2,234) of participants living in 6.0% (26/482) of households. MLVA types of all 26 S. Typhimurium stool isolates matched with corresponding MLVA types of blood isolates. The MLVA type of 1 out of 3 Enteritidis stool isolates matched with the single MLVA type of the 5 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. a human reservoir of iNTS.