Outer Membrane Protein A (OmpA) of Cronobacter sakazakii Binds Fibronectin and Contributes to Invasion of Human Brain Microvascular Endothelial Cells

Cronobacter sakazakii is an emerging foodborne pathogen that causes severe meningitis and meningoencephalitis in neonates. Currently there is a dearth of information available on the virulence factors of C. sakazakii and the pathogenic mechanisms involved in its neonatal infections. The invasion and translocation of the blood-brain barrier formed by brain microvascular endothelial cells (BMEC) is critical in the pathogenesis of neonatal bacterial meningitis. Because bacterial binding of fibronectin is an initial step in the invasion of BMEC, the role of a major surface-expressed fibronectin-binding protein of C. sakazakii in invasion of BMEC was investigated. Outer membrane protein A was identified as a major fibronectin-binding protein of C. sakazakii, and an isogenic ompA mutant of C. sakazakii exhibited significantly (p < 0.05) attenuated invasion in BMEC compared with the wild-type strain. The findings of this study indicate that outer membrane protein A is one of the determinants that contribute to C. sakazakii invasion of human BMEC in vitro, and may potentially play a role in the pathogenesis of neonatal meningitis caused by this organism.