A single amino acid substitution in PmrB is associated with polymyxin B resistance in clinical isolate of Pseudomonas aeruginosa.
Pseudomonas aeruginosa is a major causative agent of hospital-acquired infections and infections in cystic fibrosis patients. Treatment of P. aeruginosa is complicated by the presence of intrinsic and acquired multidrug-resistant isolates. Polymyxin B has often been used as the last option to treat the multidrug-resistant isolates. However, polymyxin B-resistant clinical isolates have been increasingly reported worldwide. To understand molecular details of polymyxin resistance we characterized polymyxin B-resistant clinical isolate of P. aeruginosa. The clinical isolate grew with 4 microg mL(-1) of polymyxin B while a reference P. aeruginosa PAO1 grew with 0.25 microg mL(-1). Polymyxin B susceptibility was restored (minimal inhibitory concentration from 8 to 0.5 microg mL(-1)) by an intact clone of pmrAB, but not by an intact clone of phoPQ or the cloning vector. DNA sequence analysis of pmrB from the resistant isolate revealed a single nucleotide substitution (T to C) substituted methionine to threonine at position 292 of PmrB. Involvement of this amino acid substitution in polymyxin B resistance was confirmed by complementation of a pmrAB null-mutant strain with the pmrAB containing the amino acid substitution. These results suggest that amino acid substitution in PmrB is one mechanism of polymyxin B resistance in clinical isolates of P. aeruginosa.
Abraham
Neethu
N
Department of Biology, Long Island University, NY, NY 11201, USA.
Kwon
Dong H
DH
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics*; D015169:Colony Count, Microbial; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D024881:Drug Resistance, Bacterial; D005816:Genetic Complementation Test; D006801:Humans; D050296:Microbial Viability; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D011112:Polymyxin B / Q000494:pharmacology*; D011552:Pseudomonas Infections / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000235:genetics*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; C409039:PmrB protein, bacteria; D014157:Transcription Factors; D011112:Polymyxin B