Stability inside hen eggs of a salmonella enterica serovar enteritidis bacteriophage

Background: Bacteriophages are viruses that infect bacteria and therefore are widespread in nature. Those that lyse the pathogen Salmonella enterica serovar Enteritidis (SE) should be expected in niches in which this bacterium thrives, among others the avian egg. Furthermore, bacteriophages could remain viable in this milieu. Results: Upon artificially infecting hen eggs with the SE bacteriophage f18 we found that the bacteriophage titer remains stable at least for up to 144 hrs post-infection , both in yolk and albumen at 25ºC. Conclusion: Bacteriophage f18 withstands the physico-chemical conditions of the egg inner milieu and could be considered for SE-controlling measures in the poultry industry.

Phage-resistance of Salmonella enterica serovar Enteritidis and pathogenesis in Caenorhabditis elegans is mediated by the lipopolysaccharide

Phage therapy has been used in the past as an alternative therapy against bacterial pathogens. However, phage-resistant bacterial strains can emerge. Some studies show that these phage-resistant strains are avirulent. In this study, we report that phage-resistant strains of Salmonella enterica serovar Enteritidis (hereafter S. Enteritidis) were avirulent in the Caenorhabditis elegans animal model. We isolated phage-resistant strains of S. Enteritidis ATCC 13076 by using three lytic phages (f2aSE, f3aSE and f18aSE). In these mutants, we explored different virulence factors like lipopolysaccharide (LPS), virulence plasmid (Pla), motility and type I fimbriae, all of which may have effects on virulence and could furthermore be related to phage resistance. The phage-resistant strains of S. Enteritidis showed loss of O-Polysaccharide (O-PS) and auto-agglutination, present a rough phenotype and consequently they are avirulent in the C. elegans animal model. We speculate that the O-PS is necessary for phage attachment to the S. Enteritidis cell surface.