First Description of KPC-2-Producing Escherichia coli and ST15 OXA-48-Positive Klebsiella pneumoniae in Tunisia

The aim of this study was to investigate the molecular features among Klebsiella pneumoniae and Escherichia coli strains showing a resistant/intermediate-resistant phenotype to ertapenem (R/IR-ERT), implicated in colonization/infection in patients of the Hematology and Graft Units of the National Bone Marrow Transplant Center of Tunisia (3-year period, 2011-2014). The major carbapenemase, extended-spectrum beta-lactamase, and plasmidic AmpC beta-lactamase genes were analyzed and characterized by PCR and sequencing. Genetic relatedness was determined by pulsed-field gel electrophoresis (PFGE) using XbaI and multilocus sequencing typing. The bla(OXA-48) and bla(KPC) carbapenemase genes were detected among R/IR-ERT isolates. All R/IR-ERT K. pneumoniae strains (n=19) had bla(OXA-48) gene, and 14/19 strains also harbored the bla(CTX-M-15) gene. Eight different PFGE patterns were detected among these K. pneumoniae isolates, and they showed eight different sequences types, ST11 and ST15 being the most prevalent ones. Two out of three R/IR-ERT E. coli isolates carried bla(OXA-48) and one coproduced the bla(CTX-M-15) gene. One E. coli strain, ascribed to the new sequence type ST5700, harbored the bla(KPC-2) gene. E. coli isolates were not clonally related and belonged to different sequence types (ST5700, ST227, and ST58). To our knowledge, this is the first report in Tunisia of either KPC-2 carbapenemase in E. coli or OXA-48 carbapenemase in K. pneumoniae of lineage ST15.