Invasive atypical non-typhoidalSalmonellaserovars in The Gambia

Abstract

Background Invasive non-typhoidal Salmonella (iNTS) disease continues to be a significant public health problem in sub-Saharan Africa. Common clinical misdiagnosis, frequent antimicrobial resistance, high case fatality, and lack of a vaccine make iNTS a priority for global health research. Consequently, we conducted a detailed genomic analysis of the different serovars causing invasive Salmonella diseases in rural Gambia by performing whole genome sequence analysis on 164 invasive Salmonella isolates obtained between 2008 and 2016. Results Overall, we observed changes in the incidence of invasive Salmonella disease over time and an increase in the proportion of atypical serovars causing invasive disease to 40% - 65%, relative to serovars Enteritidis and Typhimurium. Overall case fatality was rate of 10% while atypical iNTS was associated with 40% case fatality. Previously undetected genetic virulence factors, xxx, yyy, and zzz, were identified in two clades (Clade A and G), in n/N (%) of the atypical serovars. Conclusion The increase in the proportion of iNTS disease caused by atypical serovars and the high associated case fatality may be related to acquisition of specific genetic virulence factors. These factors may provide a a selective advantage to these atypical serovars. Investigations should be conducted to determine potential changes in the distribution iNTS serovars elsewhere in Africa and the extent of these virulence elements.

Genomic characterization of invasive typhoidal and non-typhoidal Salmonella in southwestern Nigeria

“…Typhimurium ST313 in Eastern Africa, but also present across the continent, including Nigeria (15,27,28), but is concordant with more recent higher S . Enteritidis reports from invasive infections in The Gambia (29). We observed that S .…”

“…However, it is more commonly reported in parts of Europe, China and USA (31). The expansion of atypical Salmonella serovars in invasive infections is associated with a high health burden (19,29).…”