title: Prevalent combination of virulence and plasmidic-encoded resistance in ST 131 Escherichia coli strains.
abstract: Escherichia coli ST131 is an important cause of multidrug-resistant infections. Thus, the aim of this study was to evaluate the concomitant presence of resistance plasmids and pathogenicity islands (PAIs) in ST131 E. coli. From 97 extraintestinal E. coli characterized for antimicrobial susceptibility and extended-spectrum β-lactamase production, 16% of isolates were identified as CTX-M-15 producers. These strains were studied by PFGE, MLST, and phylogroups, plasmid groups, PAIs, and plasmid-mediated quinolone-resistance determinants. MLST identified one ST10 strain from phylogroup A and the remaining isolates were ST131, from group B2. Despite the genetic variability, 64% of ST131 strains presented a profile composed by PAI IV₅₃₆, PAI I(CFT073), and PAI II(CFT073), IncF plasmid, bla(CTX-M-15), and aac(6')-lb-cr genes. The prevalent virulence and resistance profile detected among the strains may constitute an optimal combination of factors, which allow E. coli ST131 to maintain both features becoming concomitantly virulent and extremely resistant.
authors.affiliation: Center of Pharmaceutical Studies and Laboratory of Microbiology; Faculty of Pharmacy; University of Coimbra; Coimbra, Portugal; Service of Clinical Pathology; University Hospital of Coimbra; Coimbra, Portugal.
authors.forename: Vera
authors.initials: V
authors.lastname: Calhau
authors.affiliation: Service of Clinical Pathology; University Hospital of Coimbra; Coimbra, Portugal.
authors.forename: Graça
authors.initials: G
authors.lastname: Ribeiro
authors.affiliation: Center of Pharmaceutical Studies and Laboratory of Microbiology; Faculty of Pharmacy; University of Coimbra; Coimbra, Portugal.
authors.forename: Nuno
authors.initials: N
authors.lastname: Mendonça
authors.affiliation: Center of Pharmaceutical Studies and Laboratory of Microbiology; Faculty of Pharmacy; University of Coimbra; Coimbra, Portugal.
authors.forename: Gabriela Jorge
authors.initials: GJ
authors.lastname: Da Silva
mesh_terms: D016000:Cluster Analysis; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000145:classification* / Q000235:genetics*; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000382:microbiology; D044404:Genomic Islands; D005838:Genotype; D006801:Humans; D017720:Molecular Epidemiology; D058889:Molecular Typing; D010802:Phylogeny; D010957:Plasmids; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D037521:Virulence Factors
keywords: CTX-M-15; Escherichia coliST131; PMQR; pathogenicity island; phylogeny; plasmid replicon typing