Genome-wide identification of genes critical for in vivo fitness of multi-drug resistant porcine extraintestinal pathogenic Escherichia coli by transposon-directed insertion site sequencing using a mouse infection model

Abstract

Extraintestinal pathogenic Escherichia coli (ExPEC) is an important zoonotic pathogen. Recently, ExPEC has been reported to be an emerging problem in pig farming. However, the mechanism of pathogenicity of porcine ExPEC remains to be revealed. In this study, we constructed a transposon (Tn) mutagenesis library covering Tn insertion in over 72% of the chromosome-encoded genes of a virulent and multi-drug resistant porcine ExPEC strain PCN033. By using a mouse infection model, a transposon-directed insertion site sequencing (TraDIS) assay was performed to identify in vivo fitness factors. By comparing the Tn insertion frequencies between the input Tn library and the recovered library from different organs, 64 genes were identified to be involved in fitness during systemic infection. 15 genes were selected and individual gene deletion mutants were constructed. The in vivo fitness was evaluated by using a competitive infection assay. Among them, Δ fimG was significantly outcompeted by the WT strain in vivo and showed defective adhesion to host cells. rfa which was involved in lipopolysaccharide biosynthesis was shown to be critical for in vivo fitness which may have resulted from its role in the resistance to serum killing. In addition, several metabolic genes including fepB , sdhC , fepG , gltS , dcuA , ccmH , ddpD , narU , glpD , malM , and yabL and two regulatory genes metJ and baeS were shown as important determinants of in vivo fitness of porcine ExPEC. Collectively, this study performed a genome-wide screening for in vivo fitness factors which will be important for understanding the pathogenicity of porcine ExPEC.

Baicalin Weakens the Virulence of Porcine Extraintestinal Pathogenic Escherichia coli by Inhibiting the LuxS/AI-2 Quorum-Sensing System

“…Baicalin, a flavonoid with multiple pharmacological effects such as anti-inflammatory, antibacterial, and antioxidant activities [20,35], has proven antimicrobial properties [23,24,36,37]. However, the effect of BA on porcine ExPEC, a bacterial strain that can cause extraintestinal infections, resulting in significant economic losses in animal husbandry [38,39], has been poorly investigated. In our previous study, we observed that BA's minimum inhibitory concentration (MIC) for PCN033 was over 1600 µg/mL [32].…”

Antibacterial activity of the antimicrobial peptide PMAP-36 in combination with tetracycline against porcine extraintestinal pathogenic Escherichia coli in vitro and in vivo

“…Antimicrobial resistance is a major problem that not only threatens public health but also affects the safety of food animals [1]. Recently, ExPEC has been reported as an emerging problem in pig farming, where its incidence is increasing due to multidrug resistance, and ExPEC is causing severe infections of the central nervous system [19,20]. Therefore, there is an urgent need to develop new antimicrobial agents to combat antibiotic resistance.…”

Antibacterial activity of antimicrobial peptide PMAP-36 combined with tetracycline against porcine extraintestinal pathogenic Escherichia coli in vitro and in vivo

“…Antimicrobial resistance is a major problem which not only threaten the public health but also affect animal food safetys [15]. Recently, ExPEC has been reported as an emerging problem in pig farming, where its incidence is increasing with multi-drug resistance and causing severe infection in the central nervous system [16,17]. Therefore, there is an urgent need to develop new antimicrobial agents to decrease antibiotic resistance.…”