Scientific Publications by FDA Staff

J Med Microbiol 2014 Aug;63(Pt 8):1023-37

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

Jaradat ZW, Al Mousa W, Elbetieha A, Al Nabulsi A, Tall BD

The genus Cronobacter consists of a diverse group of Gram-negative bacilli, and is comprised of seven species: C. sakazakii, C. malonaticus, C. muytjensii, C. turicensis, C. dublinensis C. universalis, and C. condimenti. Cronobacter are regarded as opportunistic pathogens and have been implicated in newborn and infant infections causing meningitis, necrotizing enterocolitis, and bacteremia or sepsis. Its virulence is believed to be due to multiple factors. Some strains were found to produce diarrhea or cause significant fluid accumulation in suckling mice. Two iron acquisition systems (eitCBAD and iucABCD/iutA), Cronobacter plasminogen activator gene (cpa), a 17 kb type VI secretion system (T6SS), and a 27 kb filamentous hemagglutinin gene (fhaBC) and associated putative adhesins locus are harbored on a family of RepFIB-related plasmids (pESA3 and pCTU1) suggesting that these are common virulence plasmids. 98% of 229 Cronobacter spp. possessed these plasmids. Even though pESA3 and pCTU1 share a common backbone comprised of the repA gene and eitCBAD and iucABCD/iutA gene clusters, the presence of cpa, T6SS, and FHA loci depended on species; demonstrating a strong correlation with the presence of virulence traits, plasmid type, and species. Other factors were observed, in that Cronobacter form biofilms and shows unusual resistance to heat, dry, and acid stress growth conditions. The outer membrane protein A (OmpA) is probably one of the best-characterized virulence markers of Cronobacter. Furthermore, it was reported that Cronobacter employ PI3K/Akt signaling, which activates protein kinase C (PKC-alpha) and impairs the host cell's mitogen activated protein kinase pathway (MAPK) in order to invade cells. Cronobacter can also use immature dendritic cells and macrophages to escape the immune response. The objective of this review is to address the various virulence and environmental adaptive characteristics possessed by members of genus Cronobacter.