title: Multiresistant Gram-negative bacteria: the role of high-risk clones in the dissemination of antibiotic resistance.
abstract: Multilocus sequence typing reveals that many bacterial species have a clonal structure and that some clones are widespread. This underlying phylogeny was not revealed by pulsed-field gel electrophoresis, a method better suited to short-term outbreak investigation. Some global clones are multiresistant and it is easy to assume that these have disseminated from single foci. Such conclusions need caution, however, unless there is a clear epidemiological trail, as with KPC carbapenemase-positive Klebsiella pneumoniae ST258 from Greece to northwest Europe. Elsewhere, established clones may have repeatedly and independently acquired resistance. Thus, the global ST131 Escherichia coli clone most often has CTX-M-15 extended-spectrum β-lactamase (ESBL), but also occurs without ESBLs and as a host of many other ESBL types. We explore this interaction of clone and resistance for E. coli, K. pneumoniae, Acinetobacter baumannii- a species where three global lineages dominate--and Pseudomonas aeruginosa, which shows clonal diversity, but includes the relatively 'tight' serotype O12/Burst Group 4 cluster that has proved adept at acquiring resistances--from PSE-1 to VIM-1 β-lactamases--for over 20 years. In summary, 'high-risk clones' play a major role in the spread of resistance, with the risk lying in their tenacity--deriving from poorly understood survival traits--and a flexible ability to accumulate and switch resistance, rather than to constant resistance batteries.
authors.affiliation: Microbiology Services-Colindale, Health Protection Agency, London, UK.
authors.forename: Neil
authors.initials: N
authors.lastname: Woodford
authors.forename: Jane F
authors.initials: JF
authors.lastname: Turton
authors.forename: David M
authors.initials: DM
authors.lastname: Livermore
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D016000:Cluster Analysis; D024901:Drug Resistance, Multiple, Bacterial; D022761:Gene Transfer, Horizontal; D005838:Genotype; D006090:Gram-Negative Bacteria / Q000145:classification* / Q000187:drug effects* / Q000235:genetics; D016905:Gram-Negative Bacterial Infections / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission*; D006801:Humans; D017720:Molecular Epidemiology; D058889:Molecular Typing; D010802:Phylogeny
chemical_list: D000900:Anti-Bacterial Agents