Genomic Insights Into the Population and Antibiotic Resistance Changes of Salmonella Pullorum in China

Abstract

Salmonella Pullorum is a host-restricted pathogen that causes substantial economic losses in the poultry industry. This study explores the genomic characteristics of S. Pullorum based on the genomes available on GenBank, with a particular focus on its evolution and antibiotic resistance in China. The analysis reveals that most S. Pullorum strains belong to ST92 and ST2151. The S. Pullorum strains harbor a complex repertoire of virulence genes and nine antibiotic resistance genes (ARGs), including aminoglycoside resistance genes aac (6′)-Iaa, aadA5, aph (3″)-Ib, and aph (6)-Id; the tetracycline resistance gene tet(A); sulfonamide resistance genes dfrA17, sul1, and sul2; and the beta-lactam resistance gene bla_TEM-1B. The IncX1, IncQ1, and IncN plasmids play significant roles in the co-transmission of these ARGs. In addition, phylogenetic analysis indicates a closer genetic relationship among S. Pullorum strains isolated from the same country, highlighting the potential regional transmissions. Notably, S. Pullorum strains in China carry a higher number of ARGs than strains from other countries. Evolutionary dynamics reveals that the population size of S. Pullorum in China has stabilized since 2016, while the antibiotic resistance continues to rise. These results underscore the growing risk of S. Pullorum to the poultry industry and public health in China, highlighting the need for ongoing surveillance and effective control measures.