From the Guidelines
The non-classification system of Enterobacteriaceae is based on the reorganization of the family into separate families within the order Enterobacterales, due to significant genetic differences revealed by phylogenetic analyses, as reported in the most recent studies 1.
Key Points
- The previous classification systems relied heavily on biochemical and phenotypic characteristics, which sometimes grouped genetically distant organisms together.
- Modern genomic approaches, such as 16S rRNA gene sequencing and whole genome analysis, have demonstrated that these traditional methods were insufficient to accurately represent the true phylogenetic relationships among these bacteria.
- The reclassification of Enterobacteriaceae into separate families, including Erwiniaceae, Pectobacteriaceae, Yersiniaceae, Hafniaceae, Morganellaceae, and Budviciaceae, better reflects evolutionary relationships and genetic similarities between these organisms.
- The redefined Enterobacteriaceae family retains clinically important genera like Escherichia, Klebsiella, Salmonella, and Shigella.
Reason for Non-Inclusion of Previous Classifications
- Phylogenetic analyses revealed significant genetic differences that warranted reorganization, as stated in the study published in the International Journal of Antimicrobial Agents 1.
- The previous classification systems were based on biochemical and phenotypic characteristics, which were insufficient to accurately represent the true phylogenetic relationships among these bacteria.
Implications of the Non-Classification System
- The reclassification of Enterobacteriaceae has important implications for the diagnosis and management of infections caused by these organisms.
- The use of rapid testing strategies to identify specific carbapenemases and guide antibiotic therapy is strongly recommended, as reported in the study published in the International Journal of Antimicrobial Agents 1.
- The reclassification of Enterobacteriaceae highlights the need for continued advances in molecular techniques and genomic approaches to improve our understanding of the evolutionary relationships and genetic similarities between these organisms.
From the Research
Non-Classification System of Enterobacteriaceae
- The family Enterobacteriaceae has undergone significant changes in its classification system over the years, with recent studies suggesting a reclassification into seven or more separate families 2.
- Phylogenomic and comparative genomic studies have identified six main clades within the family Enterobacteriaceae, which can be reliably demarcated using molecular markers such as conserved signature indels (CSIs) 3.
- The use of 16S rRNA gene sequencing for species and strain-level microbiome analysis has been evaluated, and it has been found that full-length sequencing platforms are necessary to achieve taxonomic resolution at species and strain level 4.
Reason for Non-Inclusion of Previous Classifications
- Previous classifications of Enterobacteriaceae were based on phenotypic characteristics, which have been found to be unreliable for distinguishing between different members of the family 3.
- The use of molecular markers such as CSIs has been found to be more reliable for classifying Enterobacteriaceae, and has led to the reclassification of several polyphyletic members of the family 3.
- The recent taxonomic restructuration of Enterobacteriaceae into seven bacterial families has highlighted the need to revise and update molecular tools used for molecular microbial analyses 5.
- The changing face of the family Enterobacteriaceae, with new members, taxonomic issues, geographic expansion, and new diseases and disease syndromes, has also contributed to the non-inclusion of previous classifications 2.