Characterization of plasmids encoding blaESBL and surrounding genes in Spanish clinical isolates of Escherichia coli and Klebsiella pneumoniae

The aim of the study was to characterize plasmids that harbour bla(ESBL) genes and their genetic environment in Escherichia coli and Klebsiella pneumoniae clones circulating in Spain. The incompatibility group of plasmids within 58 strains harbouring bla(CTX-M) (n = 45) and bla(SHV) (n = 15) genes was determined by rep-typing-PCR and hybridization. The bla(ESBL) genetic environment was determined by PCR and sequencing. The bla(CTX-M-9) genes (n = 14) were linked to In60 located in IncI1 (50%) or IncHI2 plasmids (28%). All bla(CTX-M-14) genes (n = 13) were flanked by ISEcp1 and IS903 and 12 were associated with IncK plasmids. One of two bla(CTX-M-10) genes was present in an IncK plasmid, but both genes were linked to a phage-related element. Five of seven bla(CTX-M-1) (71%), all three bla(CTX-M-32) and one of two bla(CTX-M-3) genes were linked to IncN plasmids. The other bla(CTX-M-3) gene was linked to IncA/C and the remaining two bla(CTX-M-1) genes to IncFII plasmids. Three bla(CTX-M-15) genes were associated with IncF (repFIA) and one with IncFII plasmids. All these genes from bla(CTX-M) group-1 showed the ISEcp1 upstream truncated by different insertion sequences. Forty-three percent of bla(SHV-12) genes (n = 14) were located in IncI1 plasmids, all flanked by the IS26 and DEOR region. The only detected bla(SHV-5) gene was located in an IncFII plasmid and flanked by recF and DEOR regions. A diversity of the plasmid incompatibility groups that harbour bla(ESBL) genes was observed, except for the bla(CTX-M-14) gene. Moreover, a high variability was confirmed in the genetic environment of these genes as a result of insertion and deletion events.