Prevalence and distribution of non-typhoidal Salmonella enterica serogroups and serovars isolated from normally sterile sites: a global systematic review

To inform vaccine development strategies, we aimed to systematically review evidence on the prevalence and distribution of non-typhoidal Salmonella enterica serogroups and serovars. We searched four databases from inception through 4 June 2021. We included articles that reported at least one non-typhoidal Salmonella enterica strain by serogroup or serovar isolated from a normally sterile site. Of serogrouped isolates, we pooled the prevalence of serogroup O:4, serogroup O:9, and other serogroups using random-effects meta-analyses. Of serotyped isolates, we pooled the prevalence of Salmonella Typhimurium (member of serogroup O:4), Salmonella Enteritidis (member of serogroup O:9), and other serovars. Of 82 studies yielding 24,258 serogrouped isolates, pooled prevalence (95% CI) was 44.7% (36.3%-48.3%) for serogroup O:4, 45.4% (36.9%-49.0%) for serogroup O:9, and 9.9% (6.1%-13.3%) for other serogroups. Pooled prevalence (95%CI) was 36.8% (29.9%-44.0%) for Salmonella Typhimurium, 37.8% (33.2%-42.4%) for Salmonella Enteritidis, and 18.4% (11.4%-22.9%) for other serovars. Of global serogrouped non-typhoidal Salmonella isolates from normally sterile sites, serogroup O:4 and O:9 together accounted for 90%. Of global serotyped isolates, serovars Typhimurium and Enteritidis together accounted for 75%. Vaccine development strategies covering serogroups O:4 and O:9, or serovars Typhimurium and Enteritidis, have the potential to prevent the majority of non-typhoidal Salmonella invasive disease. PROSPERO:CRD42022376658. Key resultsO_LIInvasive infections in normally sterile sites caused by non-typhoidal Salmonella have a case fatality ratio of 15%. C_LIO_LIVaccine products for human non-typhoidal Salmonella are in currently in development. C_LIO_LIFor future vaccine strategies, we provide global non-typhoidal Salmonella serogroup and serovar coverage by region and by age groups. C_LIO_LISerogroups O:4 and O:9 account for 90% of isolates of non-typhoidal Salmonella enterica from normally sterile sites. C_LIO_LISerovars Typhimurium and Enteritidis, members of serogroup O:4 and O:9, respectively, cover 75% of isolates of non-typhoidal Salmonella enterica from normally sterile sites. C_LI