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Heterogeneous hydrolytic features for OXA-48-like β-lactamases
Saoussen Oueslati1, Patrice Nordmann2, Laurent Poirel3
1INSERM U914 'Emerging Resistance to Antibiotics', K.-Bicêtre, France LabEx LERMIT, Faculté de Médecine Paris Sud, K.-Bicêtre, France.
The Journal of Antimicrobial Chemotherapy
|January 14, 2015
Summary
This study compares OXA-48-like beta-lactamases, revealing variants with differing carbapenemase activities. Understanding these enzymes is crucial for combating carbapenem resistance in Enterobacteriaceae.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Carbapenem-hydrolysing class D β-lactamases (CHDLs) of the OXA-48 type are emerging resistance mechanisms in Enterobacteriaceae.
- Diverse OXA-48-like variants (e.g., OXA-162, OXA-181, OXA-163, OXA-204, OXA-232) have been identified globally, differing by minor genetic alterations.
Purpose of the Study:
- To conduct a detailed comparative analysis of the kinetic properties of various OXA-48-like β-lactamases.
- To elucidate the specific enzymatic characteristics and carbapenem resistance implications of each OXA-48-like variant.
Main Methods:
- Cloning and expression of blaOXA-48 and its variants in Escherichia coli.
- Purification of β-lactamase enzymes using ion-exchange chromatography.
- Determination of hydrolytic activities via UV spectrophotometry and measurement of minimum inhibitory concentrations (MICs) in recombinant strains.
Main Results:
- OXA-162 and OXA-204 exhibit similar hydrolytic profiles to OXA-48.
- OXA-181 demonstrates enhanced carbapenem hydrolysis, while OXA-232 shows reduced activity.
- OXA-163 efficiently hydrolyzes broad-spectrum cephalosporins but lacks significant carbapenemase activity; however, carbapenem MICs increase in porin-deficient strains.
Conclusions:
- Comparative kinetic analysis clarifies the distinct features of OXA-48-like β-lactamase variants.
- Understanding these variants is essential for predicting and managing carbapenem resistance in clinical settings.
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