Molecular characterization of Rifr mutations in Enterococcus faecalis and Enterococcus faecium

Area of Science:

• Microbiology
• Genetics
• Antimicrobial Resistance

Background:

• Acquired antibiotic resistance in enterococci is a significant public health concern.
• Mutation rates and types are critical factors in the emergence and spread of resistance.
• Understanding these mechanisms is vital for developing effective treatment strategies.

Purpose of the Study:

• To determine and compare the frequencies and types of mutations in Enterococcus faecalis and Enterococcus faecium.
• To investigate the mutation rates associated with rifampicin resistance in these enterococci species.
• To assess the potential for developing linezolid resistance based on mutation characteristics.

Main Methods:

• Minimum Inhibitory Concentrations (MICs) of rifampicin were determined using the Clinical and Laboratory Standards Institute (CLSI) agar dilution method.
• Enterococcal isolates and their rifampicin-resistant mutants were analyzed.
• Mutation frequencies and rates were calculated and compared between species.

Main Results:

• Enterococcus faecalis isolates showed no significant differences in mutation frequencies or rates.
• Enterococcus faecium exhibited mutation frequencies and rates 6.4-fold lower than E. faecalis.
• The spectrum of mutations in E. faecium B42 differed significantly from E. faecalis.
• Rifampicin resistance was linked to mutations in the rpoB gene, with higher MICs in E. faecalis mutants.

Conclusions:

• Enterococcus faecalis demonstrates a higher potential for developing linezolid resistance compared to Enterococcus faecium.
• Differences in mutation rates and types contribute to varying resistance development potentials between these species.
• The study highlights the importance of understanding mutation dynamics in antimicrobial resistance.