A nontyphoidal Salmonella serovar domestication accompanying enhanced niche adaptation

Abstract

Invasive nontyphoidal Salmonella (iNTS) causes extraintestinal infections with ~15% case fatality in many countries. However, the mechanism by which iNTS emerged in China remains unaddressed. We conducted clinical investigations of iNTS infection with recurrent treatment failure, caused by underreported Salmonella enterica serovar Livingstone (SL). Genomic epidemiology demonstrated five clades in the SL population and suggested that the international animal feed trade was a likely vehicle for their introduction into China, as evidenced by multiple independent transmission incidents. Importantly, isolates from Clade‐5‐I‐a/b, predominant in China, showed an invasive nature in mice, chicken and zebrafish infection models. The antimicrobial susceptibility testing revealed most isolates (> 96%) in China are multidrug‐resistant (MDR). Overall, we offer exploiting genomics in uncovering international transmission led by the animal feed trade and highlight an emerging hypervirulent clade with increased resistance to frontline antibiotics. The recent increase of human infections caused by invasive non‐typhoidal Salmonella, including Salmonella Livingstone, suggests their evolution towards niche adaptation to humans. This study reveals two novel subclades of S. Livingstone linked to human infections and mainly emerged in China. The recent increase of human infections caused by invasive non‐typhoidal Salmonella, including Salmonella Livingstone, suggests their evolution towards niche adaptation to humans. This study reveals two novel subclades of S. Livingstone linked to human infections and mainly emerged in China.