OXA β-lactamases

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• OXA β-lactamases, molecular class D enzymes, were initially rare, plasmid-mediated, and primarily hydrolyzed penicillins.
• Carbapenem resistance in Acinetobacter baumannii emerged in the 1980s, driven by plasmid-encoded OXA enzymes (OXA-23, OXA-40, OXA-58).

Purpose of the Study:

• To review the evolution and impact of OXA β-lactamases, particularly concerning carbapenem resistance.
• To highlight the increasing threat posed by OXA enzymes to the efficacy of carbapenem antibiotics.

Main Methods:

• Literature review of studies on OXA β-lactamases and carbapenem resistance.
• Analysis of the genetic mechanisms and spread of OXA-mediated resistance.

Main Results:

• Acinetobacter baumannii possesses chromosomally encoded OXA-51-like β-lactamases, some conferring carbapenem resistance.
• Transferable carbapenem resistance in Acinetobacter species is linked to chromosomally encoded OXA β-lactamases.
• OXA-48 β-lactamases have spread to Enterobacteriaceae, becoming a major cause of carbapenem resistance.

Conclusions:

• OXA enzymes have evolved from minor resistance factors to a major threat, diminishing the clinical utility of carbapenems.
• The rise of OXA-mediated carbapenem resistance, especially in Acinetobacter baumannii, necessitates urgent surveillance and control strategies.