%0 Journal Article %T MgrB Inactivation Is Responsible for Acquired Resistance to Colistin in Enterobacter hormaechei subsp. steigerwaltii %+ Microbiologie Fondamentale et Pathogénicité (MFP) %+ Centre de Biotechnologie de Sfax (CBS) %A Mhaya, Amel %A Bégu, Dominique %A Tounsi, Slim %A Arpin, Corinne %< avec comité de lecture %@ 0066-4804 %J Antimicrobial Agents and Chemotherapy %I American Society for Microbiology %V 64 %N 6 %P e00128-20 %8 2020 %D 2020 %R 10.1128/AAC.00128-20 %K Enterobacter cloacae complex %K Enterobacter hormaechei subsp steigerwaltii %K colistin resistance %K MgrB %K PhoPQ regulatory system %Z Life Sciences [q-bio]/Microbiology and Parasitology/Bacteriology %Z Life Sciences [q-bio]/Pharmaceutical sciences/PharmacologyJournal articles %X Multidrug-resistant strains belonging to the Enterobacter cloacae complex (ECC) group, and especially those belonging to clusters C-III, C-IV, and C-VIII, have increasingly emerged as a leading cause of health care-associated infections, with colistin used as one of the last lines of treatment. However, colistin-resistant ECC strains have emerged. The aim of this study was to prove that MgrB, the negative regulator of the PhoP/PhoQ two-component regulatory system, is involved in colistin resistance in ECC of cluster C-VIII, formerly referred to as Enterobacter hor-maechei subsp. steigerwaltii. An in vitro mutant (Eh22-Mut) was selected from a clinical isolate of Eh22. The sequencing analysis of its mgrB gene showed the presence of one nucleotide deletion leading to the formation of a truncated protein of six instead of 47 amino acids. The wild-type mgrB gene from Eh22 and that of a clinical strain of Klebsiella pneumoniae used as controls were cloned, and the corresponding recombinant plasmids were used for complementation assays. The results showed a fully restored susceptibility to colistin and confirmed for the first time that mgrB gene expression plays a key role in acquired resistance to colistin in ECC strains. %G English %2 https://hal-cnrs.archives-ouvertes.fr/hal-02980500/document %2 https://hal-cnrs.archives-ouvertes.fr/hal-02980500/file/Manuscript%20_AAC00128-20_R1_highlighted.pdf %L hal-02980500 %U https://hal-cnrs.archives-ouvertes.fr/hal-02980500 %~ CNRS