Extraintestinal pathogenic E. coli (ExPEC) include APEC (Avian pathogenic E. coli), UPEC (Uropathogenic E.coli) and NMEC (Neonatal meningitis E. coli). ExPEC cause a variety of diseases like urethritis, septicemia, meningitis, pneumonia or soft tissue infection in humans and in different animal hosts. The genetic background of E. coli is determined by Multi Locus Sequence Typing (MLST) which assigns isolates to different sequence types (STs). One particular prominent ST of ExPEC is ST95, as this ST harbors highly virulent strains. ST95 strains nearly exclusively originate from humans and birds indicating a putative host specificity of these strains. Unraveling the molecular basis of the putative host specific behavior of these highly virulent ExPEC strains, the main aim of this study was the identification of genetic markers such as single nucleotide polymorphisms (SNP) and specific phenotypic markers that discern ST95 strains according to their hosts, thereby facilitating a sound risk assessment of this group of strains in the future. In addition, this would delineate a potential zoonotic risk among these strains. To identify certain genetic markers, core genome candidate genes for SNP analysis were identified of the strains belonging to ST95 complex, and SNP analysis was performed for these candidate genes. Phenotypic assays such as adhesion, invasion assays and biofilm formation assays were performed as adhesion and invasion into the host cell provide infection strategies to bacteria, and biofilm forming capability endows bacteria with several advantages like acquisition of antibiotic resistance, expression of different virulence factors and resistance against phagocytosis and other host defence mechanisms. In summary, we could not detect any specific SNPs able to differentiate the strains of ST95 complex according to their host. Phenotypic assays showed that the avian strains of ST95 are capable of adhering and invading to other host tissues and are also able to form biofilm like those of human strains. Thus, suggesting that the avian ST95 strains have similar genetic makeups and phenotypic characters as those from humans indicates that there is a potential zoonotic risk from APEC strains and if, the avian strains have to be considered a reservoir for human ExPEC. Furthermore, these strains appear to have common ancestors.
CITATION STYLE
Drinka, P. J., Stemper, M. E., Gauerke, C. D., Miller, J. E., & Reed, K. D. (2004). Screening for Methicillin-Resistant Staphylococcus aureus in a Nursing Home. Infection Control & Hospital Epidemiology, 25(2), 95–96. https://doi.org/10.1086/503495
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