TY - JOUR
T1 - Chromosomal location of bla ctx-m genes in clinical isolates of Escherichia coli from Germany, The Netherlands and the UK
AU - Rodriguez, I.
AU - Thomas, K.M.
AU - van Essen-Zandbergen, A.
AU - Schink, A.K.
AU - Day, M.
AU - Chattaway, M.
AU - Wu, G.
AU - Mevius, D.J.
AU - Helmuth, R.
AU - Guerra, B.
PY - 2014
Y1 - 2014
N2 - This study aimed to detect and characterise clinical Escherichia coli isolates suspected of carrying chromosomally encoded CTX-M enzymes. Escherichia coli (n = 356) obtained in Germany, The Netherlands and the UK (2005–2009) and resistant to third-generation cephalosporins were analysed for the presence of ESBL-/AmpC-encoding genes within the European SAFEFOODERA-ESBL project. ß-Lactamases and their association with IS26 and ISEcp1 were investigated by PCR. Isolates were typed by phylogenetic grouping, MLST and PFGE. Plasmids were visualised by S1 nuclease PFGE, and the location of blaCTX-M genes was determined by Southern hybridisation of XbaI-, S1- and I-CeuI-digested DNA. ESBL enzymes could not be located on plasmids in 17/356 isolates (4.8%). These 17 isolates, from different countries and years, were ascribed to phylogenetic groups D (9), B2 (6) and B1 (2), and to seven sequence types, with ST38 being the most frequent (7 phylogroup D isolates). Eleven isolates produced CTX-M-15. blaCTX-M-15 genes were associated with ISEcp1. The remaining isolates expressed the CTX-M group 9 ß-lactamases CTX-M-14 (4), CTX-M-9 (1) and CTX-M-51 (1). blaCTX-M probes hybridised with I-CeuI- and/or XbaI-digested DNA, but not with S1-digested DNA, corroborating their chromosomal location. To summarise, only 4.8% of a large collection of ESBL-producing E. coli isolates harboured chromosomal blaCTX-M genes. These isolates were of human origin and belonged predominantly to ST38 and ST131, which possibly indicates the role of these sequence types in this phenomenon. However, heterogeneity among isolates was found, suggesting that their spread is not only due to the dispersion of successful E. coli clones.
AB - This study aimed to detect and characterise clinical Escherichia coli isolates suspected of carrying chromosomally encoded CTX-M enzymes. Escherichia coli (n = 356) obtained in Germany, The Netherlands and the UK (2005–2009) and resistant to third-generation cephalosporins were analysed for the presence of ESBL-/AmpC-encoding genes within the European SAFEFOODERA-ESBL project. ß-Lactamases and their association with IS26 and ISEcp1 were investigated by PCR. Isolates were typed by phylogenetic grouping, MLST and PFGE. Plasmids were visualised by S1 nuclease PFGE, and the location of blaCTX-M genes was determined by Southern hybridisation of XbaI-, S1- and I-CeuI-digested DNA. ESBL enzymes could not be located on plasmids in 17/356 isolates (4.8%). These 17 isolates, from different countries and years, were ascribed to phylogenetic groups D (9), B2 (6) and B1 (2), and to seven sequence types, with ST38 being the most frequent (7 phylogroup D isolates). Eleven isolates produced CTX-M-15. blaCTX-M-15 genes were associated with ISEcp1. The remaining isolates expressed the CTX-M group 9 ß-lactamases CTX-M-14 (4), CTX-M-9 (1) and CTX-M-51 (1). blaCTX-M probes hybridised with I-CeuI- and/or XbaI-digested DNA, but not with S1-digested DNA, corroborating their chromosomal location. To summarise, only 4.8% of a large collection of ESBL-producing E. coli isolates harboured chromosomal blaCTX-M genes. These isolates were of human origin and belonged predominantly to ST38 and ST131, which possibly indicates the role of these sequence types in this phenomenon. However, heterogeneity among isolates was found, suggesting that their spread is not only due to the dispersion of successful E. coli clones.
KW - extended-spectrum
KW - beta-lactamases
KW - coli
KW - plasmids
KW - ctx-m-15
U2 - 10.1016/j.ijantimicag.2014.02.019
DO - 10.1016/j.ijantimicag.2014.02.019
M3 - Article
VL - 43
SP - 553
EP - 557
JO - International Journal of Antimicrobial Agents
JF - International Journal of Antimicrobial Agents
SN - 0924-8579
IS - 6
ER -