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

Abstract

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.

Prevalence and Characteristics of the Epidemic Multiresistant Escherichia coli ST131 Clonal Group among Extended-Spectrum Beta-Lactamase-Producing E. coli Isolates in Copenhagen, Denmark

“…We found seven different capsular antigens among the ST131 isolates, which to our knowledge is the largest diversity of K antigens reported for ST131 to date. The only relevant precedent is from a Norwegian study that identified 3 different K antigens (K100, K14, and K5) among its 9 ST131 isolates (28). Interestingly, most of the present K100-positive isolates were initially classified presumptively by PCR as K2 based on amplification with kpsM II primers and but not with kii or K15-specific primers (18).…”

Commonality among Fluoroquinolone-Resistant Sequence Type ST131 Extraintestinal Escherichia coli Isolates from Humans and Companion Animals in Australia

“…This clonal group is an emerging human pathogen in many parts of the world, including continental Europe (3,33), the United Kingdom (28), Turkey (52), Korea (30), Canada (36,38), and the United States (18,19). Its association with bla CTX-M-15 , which encodes the CTX-M-15 extended-spectrum ␤-lactamase (ESBL), has also influenced the recent pandemic spread of extended-spectrum cephalosporin resistance (3,4,18,28,29,34,44).…”

Strain Typing and Molecular Characterization of CTX-M-1 Group ESBL in Clinical Klebsiella pneumoniae Isolated from Children

“…A high prevalence of the L/M plasmid replicon was seen in our strain collection (82.3%), although this replicon has been considered rare in CTX-M-15-expressing strains (31). Most studies have reported a dominance of IncF plasmid replicons in bla CTX-M-15 -producing strains (11,(31)(32)(33). Due to several limitations, we were unable to determine the precise location of the bla CTX-M-15 gene and it was not clear which replicon type harbored this gene.…”

“…Class 1 integrons and transferable elements like conjugative plasmids or insertion sequences (IS) (e.g., ISEcp1) play an important role in the dissemination of antimicrobial resistance genes between species or genera (10). It has been reported that bla CTX-M genes are carried on the plasmids ranging from 7 to 430 kb, mainly on large transmissible plasmids (11). Due to the role of plasmids in the horizontal transfer of antimicrobial resistance genes, much attention has been paid to the identification and classification of bacterial plasmids.…”

“…Carattoli et al demonstrated a polymerase chain reaction (PCR)-based replicon typing (PBRT) scheme to detect 18 plasmid replicons commonly found among the Enterobacteriaceae (12). The bla CTX-M types have been shown to be associated with specific plasmid replicons, for example, bla CTX-M-9 to replicon HI2, bla CTX-M-15 to replicons FII, FIA, and FIB, and bla CTX-M-3 to replicon N. In addition, different genetic elements have been shown to be involved in the mobilization of bla CTX-M , such as insertion sequence ISEcp1, which is also responsible for the expression of genes encoding β-lactamase (11). The epidemiology of CTX-M-producing strains is complex, involving the dissemination of strains and the dissemination of mobile genetic elements bearing bla CTX-M genes.…”