Plasmid-mediated quinolone resistance: a multifaceted threat

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Plasmid-mediated quinolone resistance (PMQR) has become a significant concern in recent decades.
• The qnr genes, likely originating from aquatic environments, represent the most studied PMQR mechanism.
• Emerging resistance mechanisms include aac(6 ext extprime)-Ib-cr and efflux pumps (oqxAB, qepA).

Purpose of the Study:

• To review and characterize the known mechanisms of plasmid-mediated quinolone resistance.
• To highlight the significance of PMQR in the broader context of quinolone resistance.
• To underscore the need for incorporating PMQR detection in clinical diagnostics.

Main Methods:

• Literature review of studies on PMQR genes.
• Analysis of the molecular mechanisms of qnr, aac(6 ext extprime)-Ib-cr, oqxAB, and qepA.
• Examination of the clinical implications and spread of PMQR.

Main Results:

• Qnr proteins protect DNA gyrase and topoisomerase IV from quinolone inhibition.
• aac(6 ext extprime)-Ib-cr inactivates ciprofloxacin via acetylation.
• oqxAB and qepA function as quinolone efflux pumps.
• These genes contribute to increased minimum inhibitory concentrations (MICs) and facilitate selection for higher resistance.

Conclusions:

• PMQR genes are increasingly prevalent and associated with other resistance determinants.
• The spread of PMQR is concurrent with rising clinical quinolone resistance.
• Current clinical microbiology laboratory screening methods do not account for these PMQR genes.