In: Antimicrobial Agents and Chemotherapy, 2015, vol. 59, no. 5, p. 2780–2784
A multidrug-resistant Klebsiella pneumoniae isolate exhibiting heteroresistance to colistin was investigated. The colistin-resistant subpopulation harbored a single amino acid change (Asp191Tyr) in protein PhoP, which is part of the PhoPQ two-component system that activates pmrHFIJKLM expression responsible for l-aminoarabinose synthesis and polymyxin resistance. Complementation assays with a...
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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...
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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...
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In: Antimicrobial Agents and Chemotherapy, 2016, vol. 60, no. 7, p. 4394–4397
A series of colistin-resistant Escherichia coli clinical isolates was recovered from hospitalized and community patients in South Africa. Seven clonally unrelated isolates harbored the mcr-1 gene located on different plasmid backbones. Two distinct plasmids were fully sequenced, and identical 2,600-bp-long DNA sequences defining a mcr-1 cassette were identified. Promoter sequences responsible...
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