Intestinal Carriage of Invasive Non-typhoidal Among Household Members of Children with Bloodstream Infection, Kisangani, DR Congo

Introduction: Invasive non-typhoidal (iNTS), mainly Typhimurium and Enteritidis, causes a severe burden in sub-Saharan Africa; however, its reservoir (animal or environmental) is unclear. The present study assessed healthy household members of index patients for intestinal carriage of .

Methods: Index patients were admitted to the University Hospital of Kisangani (DR Congo), and was grown from blood cultures. Household members were asked to provide three stool samples for culture for . Typhimurium and . Enteritidis isolates from index patients, and household members were assessed for genetic relatedness using the multiple-locus variable number of tandem repeat analysis (MLVA), and the multilocus sequence type (ST) was determined by whole genome sequencing.

Results: Between May 2016 and January 2020, 22 households were visited. The index patient serotypes were Typhimurium, Enteritidis, Typhi, and Paratyphi C; II:42:r:-; and I:7:y:- ( = 8, 7, 5, and each 1, respectively). The median (range) delay between the index patient and household sampling was 25 days (2 days to 7.3 months); 203 household members provided at least one stool sample. In all, 15 (7.3%) carriers were found in nine of 22 households. For one index patient, the household comprised . Typhimurium in four household members, including the index patient, sampled 27 days after bloodstream infection; the MLVA types of these five isolates were similar. They belonged to ST313 lineage 2 and were closely related [0-1 allelic distance (AD) among the stool isolates and eight AD with the blood culture isolate]. In another household, the stool culture of the index patient (obtained 67 days after bloodstream infection) grew . Enteritidis of the same MLVA type; both isolates belonged to the ST11 Central/Eastern African clade and were closely related (three AD).

Discussion: The present study provides evidence of household clustering of . Typhimurium ST313 and intestinal carriage of iNTS several weeks after bloodstream infection.