Contribution of IncFII and broad-host IncA/C and IncN plasmids to the local expansion and diversification of phylogroup B2 Escherichia coli ST131 clones carrying blaCTX-M-15 and qnrS1 genes

Abstract

The recent increase of CTX-M-15-producing Escherichia coli isolates in our institution was caused by diverse clonal backgrounds, including mainly B2 sequence type 131 (ST131) clones presenting variable virulence profiles but also A(1) (ST617, ST410), B1, and D(1) (ST405) clones. Besides IncFII-pC15-1a, we detected multidrug-resistant IncA/C(2) and IncN plasmids carrying bla(CTX-M-15) and/or qnrS1. Our study highlights the diversification of highly transmissible resistant and virulent clones and the recombinogenic potential of broad-host plasmids contributing to the expansion of genetic regions coding for multidrug resistance to other bacterial lineages.

Fig 1

PFGE profiles of XbaI-digested genomic DNA of representative CTX-M-15-producing ST131 isolates included in this study. The dendrogram was generated using the unweighted-pair group method using average linkages (UPGMA) algorithm based on the Dice similarity coefficient (1.5% optimization; 1.5% tolerance), and the vertical dotted line shows the cutoff value of 85%. The isolates possess a common pool of virulence genes (fimH, iha, sat, iutA, traT, malX, usp, fyuA, ompT) and differ in the presence of afa/draBC and kpsMTII (profile I), kpsMTII-K5 (profile II), and kpsMTII-K5, papEF, papA, papC, papGII, cnf1, and hylA (profile III). Isolation dates are shown by the day followed by the month. ^a, absence of kpsMTII. Gene definitions: fimH, type 1 fimbriae; iha, iron-regulated gene homologue adhesin; sat, secreted autotransporter toxin; iutA, ferric aerobactin receptor; traT, serum survival associated; malX, pathogenicity-associated island (PAI) marker; usp, uropathogen-specific protein; fyuA, yersiniabactin receptor; ompT, outer membrane protease; afa/draBC, Dr antigen-specific adhesin; kpsMTII, group II capsular polysaccharide; K5, variant of kpsMTII capsule; papEF, P fimbriae minor tip pilins; papA, P fimbriae major subunit, pyelonephritis associated; papC, P fimbriae assembly; papGII, papG variant, pyelonephritis associated; cnf1, cytotoxic necrotizing factor 1; and hlyA, alpha-hemolysin.