Characterization of IS26‐composite transposons and multidrug resistance in conjugative plasmids from Enterobacter cloacae

Abstract

SHV-12 is the most widespread resistance determinant of Enterobacter cloacae in Taiwan; however, bla SHV-12 has rarely been mobilized. Six multidrug-resistant E. cloacae isolates were collected. After conjugal transfer, plasmid profiling and analysis of incompatibility groups was performed to characterize the genetic context of bla SHV-12 -containing fragments. The presence of mobile genetic elements was demonstrated by PCR, cloning, sequencing and bioinformatics analyses. Four different b-lactamase genes (bla TEM-1 , bla SHV-12 , bla CTX-M-3 and/or bla CTX-M-14 ) were observed in the conjugative plasmids belonging to the IncHI2 (n ¼ 4), IncI1 or IncP incompatibility groups. The IS26-bla SHV-12 -IS26 locus was located in five different genetic environments. A novel structural organization of a class 1 integron with the aac(6')-IIc cassette truncated by IS26 was identified in one isolate. Thus, bla SHV-12 was obtained from different plasmids through IS26-mediated homologous recombination. IS26 plays a vital role in the distribution of mobile resistance elements between different plasmids found in multidrug-resistant E. cloacae isolates.

A Review of SHV Extended-Spectrum β-Lactamases: Neglected Yet Ubiquitous

“…Plasmids of this group varying in sizes (95–400 Kb) have been reported to encode bla SHV-12 in various bacterial species, such as E. coli, K. pneumoniae, E. cloacae , and at least three S. enterica serotypes (Bredeney, Concord, and Senftenberg) from human specimens with diverse geographical origin (Netherlands, Portugal, Spain, Taiwan, Tunisia; Elhani et al, 2010; Veldman et al, 2010; Herrera-Leon et al, 2011; Mnif et al, 2013; Rodrigues et al, 2014; Chen C. M. et al, 2015). Apart from bla SHV-12 , some of these conjugative plasmids have been reported to co-encode for other resistance genes, including additional SHV ESBLs ( bla CTX- M -3 , bla CTX- M -14 ; Veldman et al, 2010; Chen C. M. et al, 2015). …”

“…The range of bacterial species they have encountered is limited to E. coli, K. pneumoniae, E. cloacae , and the S. enterica serotypes Concord, Enteritidis, Heidelberg and Kiambu. Nevertheless, IncI1 plasmids (19–340 Kb) occur in very diverse settings: bla SHV-2 - and bla SHV-12 -encoding isolates from human infections (Bulgaria, France, Italy, Spain, Taiwan; Tato et al, 2007; Marcadé et al, 2009; Accogli et al, 2013; de Toro et al, 2013; Markovska et al, 2014; Chen C. M. et al, 2015) and colonization (Ethiopia) (Fabre et al, 2009); bla SHV-2 -, bla SHV-2 a –, and bla SHV-12 -encoding isolates from poultry (Canada, Italy, Portugal; Bortolaia et al, 2010, 2011; Accogli et al, 2013; Pouget et al, 2013; Jones-Dias et al, 2015), bla SHV-2 - and bla SHV-2 a -encoding isolates from pigs (Canada) (Pouget et al, 2013); bla SHV-12 -encoding isolates from aquatic birds (Poland) (Literak et al, 2010); and bla SHV-12 -encoding isolates from farming soil (Portugal) (Jones-Dias et al, 2016). Remarkably, bla SHV-12 on IncI1 plasmids belonging to pST26 have been identified among E. coli isolates of human and animal origin (Accogli et al, 2013; Jones-Dias et al, 2015), indicating the potential transmission of these bla SHV-12 -encoding vehicles from human to animals and/or vice versa.…”

“…bla SHV-12 has been incidentally found on: (i) a ColE plasmid from S. enterica serotype Typhimurium DT104b in Spain (Herrera-Leon et al, 2011); (ii) an IncK plasmid from K. pneumoniae in the United Kingdom (Timofte et al, 2014); (iii) an IncP plasmid from E. cloacae in Taiwan (Chen C. M. et al, 2015); and (iv) a plasmid assigned to the R replicon type from K. pneumoniae in Portugal (Rodrigues et al, 2014). E. coli and K. pneumoniae encoding bla SHV-2 on IncK plasmids were recovered from animal and human sources in the Netherlands and in Uruguay, respectively (Dierikx et al, 2010; García-Fulgueiras et al, 2011).…”

“…Similarly to most antibiotic resistance genes, IS 26 -mediated mobilization of SHV ESBL genes on conjugative plasmids facilitated their subsequent intra- and inter-species dissemination (Table 4). Available sequences of transposons flanked by copies of intact and/or truncated IS 26 elements (Figure 3) and coding for SHV ESBL genes show the presence of other co-linear genes originating from the chromosome of K. pneumoniae (i.e., fucA, ygbI, ygbK, ygbJ, ygbM, deoR ; Ho et al, 2012; Wang et al, 2012; Du et al, 2013; Kassis-Chikhani et al, 2013; Preston et al, 2014; Chen C. M. et al, 2015; Feng et al, 2015; Giakkoupi et al, 2015), likely underscoring the involvement of IS 26 in the mobilization of bla SHV from the chromosome of K. pneumoniae , as previously suggested (Haeggman et al, 1997). …”

“…Map is not to scale. References: IncN (Wang et al, 2012); IncA/C (Giakkoupi et al, 2015); IncL/M (Preston et al, 2014); IncHI2, IncI1, IncP (Chen C. M. et al, 2015); IncX3 (Ho et al, 2012; Du et al, 2013; Kassis-Chikhani et al, 2013; Feng et al, 2015). …”