International audienceFluoroquinolones (FQ) are potential treatments to treat infections from extended-spectrum β-lactamase producing-Enterobacteriaceae susceptible to FQ. Due to increasing non-susceptibility to carbapenems among Enterobacteriaceae, we characterized FQ resistance mechanisms in 36 Klebsiella pneumoniae isolates that are non-susceptible to ertapenem in North-Eastern France in 2012 and described the population structure by pulsed field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). Among them, 36% (13/36) carried a carbapenemase encoding-gene. Decreased expression of the OmpK35 encoding-gene might be considered a major resistance determinant that could explain non-susceptibility to carbapenems. The carbapenemase-producing isolates carried the well-known IncL pOXA48a plasmid. All the K. pneumoniae (36/36) isolates also harbored a fluoroquinolone-resistant (FQ-R) determinant. aac(6')-Ib-cr was the major plasmid-mediated quinolone resistant (PMQR) determinant found in K. pneumoniae (86%, 32/36). The MLST study identified 5 sequence types (STs). The most dominant ST was ST395 (25/36) followed by ST147 (6/36). ST395 strains showed ertapenem minimum inhibitory concentrations (MICs) ranging from 0.75μg/mL to 32μg/mL.K. pneumoniae ST395 did not show enhanced biofilm formation, nor environmental survival, but showed higher chlorhexidine MICs than the ST147 isolates. These findings showed that (i) K. pneumoniae ST395 carrying pOXA-48a has spread in North-Eastern France, (ii) aac(6')-Ib-cr is preponderant in carbapenem non-susceptible K. pneumoniae, (iii) K. pneumoniae ST395 is resistant to chlorhexidine, and (iv) FQ as alternatives to β-lactams to treat ertapenem non-susceptible K. pneumoniae are compromised
