Cronobacter spp. (previously Enterobacter sakazakii) invade and translocate across both cultured human intestinal epithelial cells and human brain microvascular endothelial cells

Abstract

a b s t r a c tThe mechanism of Cronobacter pathogenesis in neonatal meningitis and potential virulence factors (aside from host cell invasion ability) remain largely unknown. To ascertain whether Cronobacter can invade and transcytose across intestinal epithelial cells, enter into the blood stream and then transcytose across the blood-brain-barrier, we have utilized human intestinal INT407 and Caco-2 cells and brain microvascular endothelial cell (HBMEC) monolayers on Transwell filters as experimental model systems. Our data indicate a wide range of heterogeneity with respect to invasion efficiency among twenty-three Cronobacter isolates screened. For selected isolates, we observed significant levels of transcytosis for Cronobacter sakazakii across tight monolayers of both Caco-2 and HBMEC, mimicking in vivo ability to cross the intestine as well as the blood brain barrier, and at a frequency equivalent to that of a control meningitis-causing Escherichia coli K1 strain. Finally, EM analysis demonstrated intracellular Cronobacter bacteria within host vacuoles in HBMEC, as well as transcytosed bacteria at the basolateral surface. These data reveal that certain Cronobacter isolates can invade and translocate across both cultured human intestinal epithelial cells and HBMEC, thus demonstrating a potential path for neonatal infections of the central nervous system (CNS) following oral ingestion.Published by Elsevier Ltd.

Cronobacter spp. – opportunistic food-borne pathogens. A review of their virulence and environmental-adaptive traits

“…Nonetheless, not all Cronobacter spp. were positive for OmpA using the primers described by Nair & Venkitanarayanan (2007), as reported by Jaradat et al (2009) and Giri et al (2012).…”

“…is dose-dependent, but not due to a property of a particular bacterial species as a whole, rather a characteristic(s) of certain strains, which may be innocuous in a full-term, yet pathogenic in a pre-term infant (Hamby et al, 2011;Cetinkaya et al, 2013). In vitro models of infection also suggest that the organism may also gain entrance into the systemic circulation through transcytosis of the GIT epithelium (Giri et al, 2012).…”

“…Kim & Loessner (2008) found that Cronobacter entry into and invasion of Caco-2 cells is an active process that needs de novo protein synthesis, and depends on exposure time and m.o.i. Recently, Giri et al (2012) demonstrated that Cronobacter isolates were able to transcytose across tight monolayers of Caco-2 cells and HBMECs, thus mimicking the in vivo ability to cross the intestine and subsequently the CNS BBB to cause meningitis. Not only that, the rate of transcytosis of some strains was equivalent to that of the control meningitis-causing E. coli K1 strain.…”

“…Attachment of Cronobacter to certain cell lines and the subsequent invasion were the focus of several reports in an attempt to understand the pathogenicity mechanisms of this pathogen (Mange et al, 2006;Kim & Loessner, 2008;Singamsetty et al, 2008;Townsend et al, 2008;Giri et al, 2012). Therefore, the objective of this review is to address the various virulence characteristics of members of the genus Cronobacter that contribute to its contamination of foods, and survival in the environment and host.…”

Cronobacter sakazakii: stress survival and virulence potential in an opportunistic foodborne pathogen

“…13 A more recent study observed significant levels of transcytosis across a tight monolayer of HBMEC and included electron-microscopic analysis demonstrating the presence of Cronobacter within host vacuoles of HBMEC, in addition to being trancytosed at the basolateral surface. 88 While significant strain variation was noted, this study further contributes to our understanding of how this gastrointestinal pathogen penetrates the blood brain barrier (BBB) and ultimately causes meningitis. The previously mentioned OmpA protein, which plays a role in attachment of C. sakazakii to the gastrointestinal tract, has also been implicated in the invasion of HBMEC.…”