The taxonomy of Enterobacter sakazakii: proposal of a new genus Cronobacter gen. nov. and descriptions of Cronobacter sakazakii comb. nov. Cronobacter sakazakii subsp. sakazakii, comb. nov., Cronobacter sakazakii subsp. malonaticus subsp. nov., Cronobacter turicensis sp. nov., Cronobacter muytjensii sp. nov., Cronobacter dublinensis sp. nov. and Cronobacter genomospecies 1

Abstract

Background Enterobacter sakazakii is an opportunistic pathogen that can cause infections such as necrotizing enterocolitis, bacteraemia, meningitis and brain abscess/lesions. When the species was defined in 1980, 15 biogroups were described and it was suggested that these could represent multiple species. In this study the taxonomic relationship of strains described as E. sakazakii was further investigated. Results Strains identified as E. sakazakii were divided into separate groups on the basis of f-AFLP fingerprints, ribopatterns and full-length 16S rRNA gene sequences. DNA-DNA hybridizations revealed five genomospecies. The phenotypic profiles of the genomospecies were determined and biochemical markers identified. Conclusion This study clarifies the taxonomy of E. sakazakii and proposes a reclassification of these organisms.

Cronobacter sakazakii (Enterobacter sakazakii): An Emerging Foodborne Pathogen

“…This bacteria is facultative anaerobic and generally peritrichous. Cronobacter sakazakii is generally indole, dulcitol and malonate negative, but methyl-α-D glucopyranoside positive 22 . The activity of α-glucosidase has been implemented as a selective marker in differential chromogenic agar 25 .…”

“…E. sakazakii isolates were reclassified in the novel genus, Cronobacter in 2008. Currently there are five distinct species in the genus, namely Cronobacter sakazakii, Cronobacter malonaticus, Cronobacter turicensis, Cronobacter dublinensis and Cronobacter muytjensii 22 . The strains of C. sakazakii are allocated in biogroups 1-4, 7, 8, 11 and 13 30 .…”

“…Currently there are five distinct species in the genus, namely Cronobacter sakazakii, Cronobacter malonaticus, Cronobacter turicensis, Cronobacter dublinensis and Cronobacter muytjensii 22 . The strains of C. sakazakii are allocated in biogroups 1-4, 7, 8, 11 and 13 30 . Cronobacter malonaticus is the closest related to C. sakazakii of all the Cronobacter species 31 and is characterized by the utilization of malonate 32 .…”

“…dublinensis contains strains from biogroup 6 and the type strain was isolated from an environmental sample in a milk processing facility. The strains from these three subspecies were grouped together with sequence analysis based on 16S rRNA, F-AFLP and ribotyping 22 . Based on these results the three biogroups were designated as three subspecies 33 .…”

“…It was suggested by Lai 9 that this resistance was likely due to the overall increasing trend of antibiotic resistance in members of the Enterobacteriaceae in general. It has been determined that API 20E biochemical kits are not reliable or consistent tools for the correct identification of Cronobacter strains 21,22 . The polymerase chain reaction (PCR) has been shown to be a more reliable approach to identifying Cronobacter in comparison with the conventional identification techniques 23,24 .…”