The emerging problem of linezolid-resistant enterococci.

Area of Science:

• Infectious Diseases
• Microbiology
• Antimicrobial Resistance

Background:

• Enterococcus species are major causes of nosocomial infections.
• Linezolid (LNZ) is a critical antibiotic for treating infections caused by Gram-positive bacteria, including vancomycin-resistant enterococci.
• The emergence of linezolid-resistant enterococci (LRE) poses a significant clinical challenge.

Purpose of the Study:

• To systematically review and characterize the epidemiological, microbiological, and clinical features of linezolid-resistant enterococci (LRE) infections.
• To identify factors associated with the development of LRE.
• To understand the genetic mechanisms conferring LNZ resistance in Enterococcus.

Main Methods:

• Systematic literature review of studies reporting on LNZ-resistant enterococci (LRE).
• Analysis of epidemiological data, including patient LNZ exposure history.
• Examination of microbiological data, focusing on genetic mutations (e.g., 23S rRNA) and resistance genes (e.g., cfr, optrA).

Main Results:

• Linezolid (LNZ) maintains high susceptibility rates (99.8% and 99.2%) in major surveillance programs.
• Prior LNZ exposure was common in patients with LRE, with prolonged treatment durations observed.
• Mechanisms of LNZ resistance include 23S rRNA mutations (G2576T) and the presence of cfr and optrA genes, with potential for horizontal gene transfer.

Conclusions:

• The emergence of LRE, driven by factors including prior LNZ use and specific resistance genes, complicates treatment.
• Continued global surveillance is essential to monitor the prevalence of LRE and novel resistance mechanisms.
• Further research is needed to fully elucidate the prevalence and impact of emerging resistance genes.