Mainstreams of horizontal gene exchange in enterobacteria: consideration of the outbreak of enterohemorrhagic E. coli O104:H4 in Germany in 2011

• Published in: PloS one Vol. 6; no. 10; p. e25702
• Main Authors: Bezuidt, Oliver, Pierneef, Rian, Mncube, Kingdom, Lima-Mendez, Gipsi, Reva, Oleg N
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 14-10-2011; Public Library of Science (PLoS)
• Subjects: Animals; Antibiotic resistance; Antibiotics; Bacteria; Base Sequence; Biochemistry; Bioinformatics; Biology; Cattle; Chromosomes; Cluster Analysis; CpG Islands - genetics; Deoxyribonucleic acid; Disease Outbreaks; DNA; Drug resistance; E coli; Enterohemorrhagic Escherichia coli - genetics; Environmental monitoring; Escherichia coli; Escherichia coli Infections - epidemiology; Escherichia coli Infections - genetics; Escherichia coli Infections - microbiology; Evolution; Exchanging; Fitness; Fluxes; Gene transfer; Gene Transfer, Horizontal - genetics; Genes; Genetic engineering; Genomes; Genomic islands; Genomics; Germany - epidemiology; Humans; Microbial drug resistance; Microbiota (Symbiotic organisms); Microflora; Migration; Molecular Sequence Annotation; Oscillations; Outbreaks; Pathogens; Penetration resistance; Phylogenetics; Plasmids; Plasmids - genetics; Pseudomonas aeruginosa; Recombination; Recombination hot spots; Reproductive fitness; Sequence Homology, Nucleic Acid; Transposons; Virulence; Virulence (Microbiology); Germany
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0025702

Escherichia coli O104:H4 caused a severe outbreak in Europe in 2011. The strain TY-2482 sequenced from this outbreak allowed the discovery of its closest relatives but failed to resolve ways in which it originated and evolved. On account of the previous statement, may we expect similar upcoming outbreaks to occur recurrently or spontaneously in the future? The inability to answer these questions shows limitations of the current comparative and evolutionary genomics methods.
The study revealed oscillations of gene exchange in enterobacteria, which originated from marine γ-Proteobacteria. These mobile genetic elements have become recombination hotspots and effective 'vehicles' ensuring a wide distribution of successful combinations of fitness and virulence genes among enterobacteria. Two remarkable peculiarities of the strain TY-2482 and its relatives were observed: i) retaining the genetic primitiveness by these strains as they somehow avoided the main fluxes of horizontal gene transfer which effectively penetrated other enetrobacteria; ii) acquisition of antibiotic resistance genes in a plasmid genomic island of β-Proteobacteria origin which ontologically is unrelated to the predominant genomic islands of enterobacteria.
Oscillations of horizontal gene exchange activity were reported which result from a counterbalance between the acquired resistance of bacteria towards existing mobile vectors and the generation of new vectors in the environmental microflora. We hypothesized that TY-2482 may originate from a genetically primitive lineage of E. coli that has evolved in confined geographical areas and brought by human migration or cattle trade onto an intersection of several independent streams of horizontal gene exchange. Development of a system for monitoring the new and most active gene exchange events was proposed.