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

Objectives: 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. Methods: 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. Results: The bla CTX-M-9 genes (n = 14) were linked to In60 located in Incl1 (50%) or lncHl2 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 CTC-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 Incl1 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 recFand DEOR regions. Conclusions: 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.