Molecular characterization of CTX-M-15-producing clinical isolates of Escherichia coli reveals the spread of multidrug-resistant ST131 (O25:H4) and ST964 (O102:H6) strains in Norway.
Nationwide, CTX-M-producing clinical Escherichia coli isolates from the Norwegian ESBL study in 2003 (n=45) were characterized on strain and plasmid levels. Bla(CTX-M) allele typing, characterization of the genetic environment, phylogenetic groups, pulsed field gel electrophoresis (PFGE), serotyping and multilocus sequence typing were performed. Plasmid analysis included S1-nuclease-PFGE, polymerase chain reaction-based replicon typing, plasmid transfer and multidrug resistance profiling. Bla(CTX-M-15) (n=23; 51%) and bla(CTX-M-14) (n=11; 24%) were the major alleles of which 18 (78%) and 6 (55%), respectively, were linked to ISEcp1. Thirty-two isolates were of phylogenetic groups B2 and D. Isolates were of 29 different XbaI-PFGE-types including six regional clusters. Twenty-three different O:H serotypes were found, dominated by O25:H4 (n=9, 20%) and O102:H6 (n=9, 20%). Nineteen different STs were identified, where ST131 (n=9, 20%) and ST964 (n=7, 16%) were dominant. Bla(CTX-M) was found on > or =100 kb plasmids (39/45) of 10 different replicons dominated by IncFII (n=39, 87%), FIB (n=20, 44%) and FIA (n=19, 42%). Thirty-nine isolates (87%) displayed co-resistance to other classes of antibiotics. A transferable CTX-M phenotype was observed in 9/14 isolates. This study reveals that the majority of CTX-M-15-expressing strains in Norway are part of the global spread of multidrug-resistant ST131 and ST-complex 405, associated with ISEcp1 on transferrable IncFII plasmids.
Naseer
Umaer
U
Reference Centre for Detection of Antimicrobial Resistance (K-res), Department of Microbiology and Infection Control, University Hospital of North-Norway, Tromsø, Norway. Umaer.Naseer@fagmed.uit.no
Haldorsen
Bjørg
B
Tofteland
Ståle
S
Hegstad
Kristin
K
Scheutz
Flemming
F
Simonsen
Gunnar Skov
GS
Sundsfjord
Arnfinn
A
D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D015180:Electrophoresis, Gel, Two-Dimensional; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D009664:Norway / Q000453:epidemiology; D019081:O Antigens / Q000096:biosynthesis / Q000235:genetics; D010802:Phylogeny; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction; D015995:Prevalence; D011446:Prospective Studies; D012703:Serotyping; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology
D004269:DNA, Bacterial; D019081:O Antigens; C473109:beta-lactamase CTX-M-15; D001618:beta-Lactamases