Université de Fribourg

High-level resistance to colistin mediated by various mutations in the crrb gene among carbapenemase-producing klebsiella pneumoniae

Jayol, Aurélie ; Nordmann, Patrice ; Brink, Adrian ; Villegas, Maria-Virginia ; Dubois, Véronique ; Poirel, Laurent

In: Antimicrobial Agents and Chemotherapy, 2017, vol. 61, no. 11, p. e01423-17

Mutations in crrAB genes encoding a two-component regulator involved in modifications of lipopolysaccharide were searched for among a collection of colistin- resistant Klebsiella pneumoniae isolates. Four isolates, respectively, producing carbapenemases NDM-1, OXA-181, or KPC-2 showed mutated CrrB proteins compared with those in wild-type strains. Complementation assays with a wild-type CrrB...

Université de Fribourg

Modulation of mgrB gene expression as a source of colistin resistance in Klebsiella oxytoca

Jayol, Aurélie ; Poirel, Laurent ; Villegas, Maria-Virginia ; Nordmann, Patrice

In: International Journal of Antimicrobial Agents, 2015, vol. 46, no. 1, p. 108–110

Gene modifications in the PmrAB and PhoPQ two-component regulatory systems, as well as inactivation of the mgrB gene, are known to be causes of colistin resistance in Klebsiella pneumoniae. The objective of this study was to characterise the mechanism involved in colistin resistance in a Klebsiella oxytoca isolate. A K. oxytoca clinical isolate showing resistance to colistin was recovered in...

Université de Fribourg

The mgrB gene as a key target for acquired resistance to colistin in Klebsiella pneumoniae

Poirel, Laurent ; Jayol, Aurélie ; Bontron, Séverine ; Villegas, Maria-Virginia ; Ozdamar, Melda ; Türkoglu, Salih ; Nordmann, Patrice

In: Journal of Antimicrobial Chemotherapy, 2014, p. dku323

Objectives Alterations in the PhoPQ two-component regulatory system may be associated with colistin resistance in Klebsiella pneumoniae. MgrB is a small transmembrane protein produced upon activation of the PhoPQ signalling system, and acts as a negative regulator on this system. We investigated the role of the MgrB protein as a source of colistin resistance in a series of K. pneumoniae.Methods...

Université de Fribourg

Resistance to colistin associated with a single amino acid change in protein PmrB among Klebsiella pneumoniae isolates of worldwide Origin

Jayol, Aurélie ; Poirel, Laurent ; Brink, Adrian ; Villegas, Maria-Virginia ; Yilmaz, Mesut ; Nordmann, Patrice

In: Antimicrobial Agents and Chemotherapy, 2014, vol. 58, no. 8, p. 4762–4766

A series of colistin-resistant Klebsiella pneumoniae isolates recovered from different countries was investigated in order to evaluate the involvement of the PmrA/PmrB two-component system in this resistance. Six isolates possessed a mutated PmrB protein, which is encoded by the pmrB gene, part of the pmrCAB operon involved in lipopolysaccharide modification. The same amino acid substitution...