Investigation article published in International Journal of Food Microbiology

August 17^th, 2012

Enterococcus faecalis is a nosocomial opportunistic pathogen, but is also found in fermented food products where it plays a fundamental role in the fermentation process. Previously, we have described the non-starter E. faecalis cheese isolate QA29b as harboring virulence genes and proven to be virulent in Galleria mellonella virulence model. In this study, we further characterized this food strain concerning traits relevant for the host-pathogen relationship. QA29b was found to belong to sequence type (ST) 72, a common ST among food isolates, and thus we consider it as a good representative of food E. faecalis strains. It demonstrated high ability to form biofilms, to adhere to epithelial cells and was readily eliminated by J774.A1 macrophage cells. Despite carrying the cps locus associated with the capsular polysaccharide CPS 2 type, cps genes were not expressed, likely due to an IS6770 inserted in the cpsC-cpsK promoter region. This work constitutes the first study of traits important for interaction, colonization and infection in the host performed on a good representative of E. faecalis food isolates. Reported results stress the need for a reliable serotyping assay of E. faecalis, as cps genotyping may not be reliable. Overall, QA29b characterization shows that despite its virulence potential in an insect model, this food strain is readily eliminated by mammalian macrophages. Thus, fine tuned approaches combining cellular and mammalian models are needed to address and elucidate the multifactorial aspect of virulence potential associated with food isolates

Gaspar FB., Montero N., Akary E., Teixeira N., Matos R., Gonzalez-Zorn B., Barreto-Crespo MT., Serror P. and Silva Lopes MF.

Incongruence between the cps type 2 genotype and host-related phenotypes of an Enterococcus faecalis food isolate

Incongruence between the cps type 2 genotype and host-related phenotypes of an Enterococcus faecalis food isolate

	Servicio de Zoonosis de Transmisión Alimentaria y Resistencia a Antimicrobianos (ZTA). Centro de Vigilancia Sanitaria Veterinaria (VISAVET). Universidad Complutense (UCM).
	Departamento de Sanidad Animal. Facultad de Veterinaria. Universidad Complutense (UCM).
	Instituto de Tecnologia Química e Biológica (ITQB). Universidade Nova de Lisboa (UNL).
	Instituto Nacional de Investigación Agronómica de Francia (INRA).
	Institut des Sciences et Industries du Vivant et de L´environnement (AgroParisTech).
	Instituto de Biología Experimental Tecnológica (IBET).