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OXA-14, another extended-spectrum variant of OXA-10 (PSE-2) beta-lactamase from Pseudomonas aeruginosa
1Department of Medical Microbiology, London Hospital Medical College, United Kingdom.
Abstract:
Pseudomonas aeruginosa 455, isolated in Ankara, Turkey, produced a pI 6.2 beta-lactamase determined by plasmid pMLH53 and resisted all beta-lactams except carbapenems. This beta-lactamase, named OXA-14, corresponded to OXA-10 (PSE-2) except that aspartate replaced glycine at position 157 and thus is intermediate between OXA-10 and OXA-11, which has aspartate at position 157 and a further substitution at position 143.
Insights
A novel beta-lactamase, OXA-14, was identified in Pseudomonas aeruginosa from Turkey. This enzyme confers resistance to most beta-lactams, except carbapenems, due to specific amino acid substitutions.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen known for its intrinsic and acquired resistance to antibiotics.
- Beta-lactamases are enzymes that hydrolyze beta-lactam antibiotics, a major mechanism of resistance.
- The emergence of novel beta-lactamases necessitates continuous surveillance and characterization.
Purpose of the Study:
- To characterize a newly identified beta-lactamase produced by Pseudomonas aeruginosa.
- To determine the genetic basis and resistance profile of the novel enzyme.
Main Methods:
- Isolation and identification of Pseudomonas aeruginosa strain 455 from Ankara, Turkey.
- Plasmid DNA extraction and characterization (plasmid pMLH53).
- Determination of beta-lactamase isoelectric point (pI) and substrate resistance profile.
- Comparison of the novel beta-lactamase sequence with known OXA-type enzymes.
Main Results:
- A Pseudomonas aeruginosa strain (455) produced a beta-lactamase with a pI of 6.2, encoded by plasmid pMLH53.
- The identified beta-lactamase, named OXA-14, conferred resistance to all tested beta-lactams except carbapenems.
- OXA-14 showed structural similarity to OXA-10 (PSE-2) but with a key amino acid substitution (Gly157Asp).
- OXA-14 is structurally intermediate between OXA-10 and OXA-11, differing at positions 157 and 143.
Conclusions:
- A novel OXA-type beta-lactamase, OXA-14, has been identified in Pseudomonas aeruginosa.
- OXA-14 contributes to the resistance of Pseudomonas aeruginosa to a broad spectrum of beta-lactam antibiotics.
- The specific amino acid substitutions in OXA-14 highlight the evolutionary diversity of beta-lactamases and their potential to evade antibiotic therapy.