Invasiveness as a putative additional virulence mechanism of some atypical Enteropathogenic <it>Escherichia coli </it>strains with different uncommon intimin types

• Main Authors: Blanco Jesús E, Dahbi Ghizlane, Carneiro Sylvia M, Schmidt M Alexander, Greune Lilo, Blanco Miguel, Hernandes Rodrigo T, Yamamoto Denise, Mora Azucena, Blanco Jorge, Gomes Tânia AT
• Format: Article
• Language: English
• Published: BMC 2009-07-01
• Series: BMC Microbiology
• Online Access: http://www.biomedcentral.com/1471-2180/9/146

<p>Abstract</p> <p>Background</p> <p>Enteropathogenic <it>Escherichia coli </it>(EPEC) produce attaching/effacing (A/E) lesions on eukaryotic cells mediated by the outer membrane adhesin intimin. EPEC are sub-grouped into typical (tEPEC) and atypical (aEPEC). We have recently demonstrated that aEPEC strain 1551-2 (serotype O non-typable, non-motile) invades HeLa cells by a process dependent on the expression of intimin sub-type omicron. In this study, we evaluated whether aEPEC strains expressing other intimin sub-types are also invasive using the quantitative gentamicin protection assay. We also evaluated whether aEPEC invade differentiated intestinal T84 cells.</p> <p>Results</p> <p>Five of six strains invaded HeLa and T84 cells in a range of 13.3%–20.9% and 5.8%–17.8%, respectively, of the total cell-associated bacteria. The strains studied were significantly more invasive than prototype tEPEC strain E2348/69 (1.4% and 0.5% in HeLa and T84 cells, respectively). Invasiveness was confirmed by transmission electron microscopy. We also showed that invasion of HeLa cells by aEPEC 1551-2 depended on actin filaments, but not on microtubules. In addition, disruption of tight junctions enhanced its invasion efficiency in T84 cells, suggesting preferential invasion via a non-differentiated surface.</p> <p>Conclusion</p> <p>Some aEPEC strains may invade intestinal cells <it>in vitro </it>with varying efficiencies and independently of the intimin sub-type.</p>