title: The increasing threat of Pseudomonas aeruginosa high-risk clones.
abstract: The increasing prevalence of chronic and hospital-acquired infections produced by multidrug-resistant (MDR) or extensively drug-resistant (XDR) Pseudomonas aeruginosa strains is associated with significant morbidity and mortality. This growing threat results from the extraordinary capacity of this pathogen for developing resistance through chromosomal mutations and from the increasing prevalence of transferable resistance determinants, particularly those encoding carbapenemases or extended-spectrum β-lactamases (ESBLs). P. aeruginosa has a nonclonal epidemic population structure, composed of a limited number of widespread clones which are selected from a background of a large quantity of rare and unrelated genotypes that are recombining at high frequency. Indeed, recent concerning reports have provided evidence of the existence of MDR/XDR global clones, denominated high-risk clones, disseminated in hospitals worldwide; ST235, ST111, and ST175 are likely those more widespread. Noteworthy, the vast majority of infections by MDR, and specially XDR, strains are produced by these and few other clones worldwide. Moreover, the association of high-risk clones, particularly ST235, with transferable resistance is overwhelming; nearly 100 different horizontally-acquired resistance elements and up to 39 different acquired β-lactamases have been reported so far among ST235 isolates. Likewise, MDR internationally-disseminated epidemic strains, such as the Liverpool Epidemic Strain (LES, ST146), have been noted as well among cystic fibrosis patients. Here we review the population structure, epidemiology, antimicrobial resistance mechanisms and virulence of the P. aeruginosa high-risk clones. The phenotypic and genetic factors potentially driving the success of high-risk clones, the aspects related to their detection in the clinical microbiology laboratory and the implications for infection control and public health are also discussed.
authors: Servicio de Microbiología and Unidad de Investigación, Hospital Universitario Son Espases, Instituto de Investigación Sanitaria de Palma (IdISPa), Ctra. Valldemossa 79, 07010 Palma de Mallorca, Spain. Electronic address: antonio.oliver@ssib.es.
authors: Antonio
authors: A
authors: Oliver
authors: Servicio de Microbiología and Unidad de Investigación, Hospital Universitario Son Espases, Instituto de Investigación Sanitaria de Palma (IdISPa), Ctra. Valldemossa 79, 07010 Palma de Mallorca, Spain.
authors: Xavier
authors: X
authors: Mulet
authors: Servicio de Microbiología and Unidad de Investigación, Hospital Universitario Son Espases, Instituto de Investigación Sanitaria de Palma (IdISPa), Ctra. Valldemossa 79, 07010 Palma de Mallorca, Spain.
authors: Carla
authors: C
authors: López-Causapé
authors: Servicio de Microbiología and Unidad de Investigación, Hospital Universitario Son Espases, Instituto de Investigación Sanitaria de Palma (IdISPa), Ctra. Valldemossa 79, 07010 Palma de Mallorca, Spain.
authors: Carlos
authors: C
authors: Juan
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002999:Clone Cells; D003428:Cross Infection / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D024901:Drug Resistance, Multiple, Bacterial; D005838:Genotype; D006801:Humans; D017720:Molecular Epidemiology; D015995:Prevalence; D011552:Pseudomonas Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D000900:Anti-Bacterial Agents
keywords: Epidemic clones; High-risk clones; International clones; Molecular epidemiology; Multidrug resistance; Pseudomonas aeruginosa; ST111; ST175; ST235