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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
Author(s) -
NASEER UMAER,
HALDORSEN BJØRG,
TOFTELAND STÅLE,
HEGSTAD KRISTIN,
SCHEUTZ FLEMMING,
SIMONSEN GUNNAR SKOV,
SUNDSFJORD ARNFINN
Publication year - 2009
Publication title -
apmis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.909
H-Index - 88
eISSN - 1600-0463
pISSN - 0903-4641
DOI - 10.1111/j.1600-0463.2009.02465.x
Subject(s) - plasmid , pulsed field gel electrophoresis , biology , multilocus sequence typing , typing , multiple drug resistance , microbiology and biotechnology , serotype , escherichia coli , phylogenetic tree , genetics , drug resistance , genotype , gene
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 IS Ecp1 . Thirty‐two isolates were of phylogenetic groups B2 and D. Isolates were of 29 different Xba I‐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 ≥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 IS Ecp1 on transferrable IncFII plasmids.