Genetic changes that correlate with reduced susceptibility to daptomycin in Staphylococcus aureus

Area of Science:

• Microbiology
• Genetics
• Pharmacology

Background:

• Daptomycin is a critical lipopeptide antibiotic for treating Gram-positive bacterial infections.
• Understanding the mechanisms of daptomycin resistance is crucial for effective treatment strategies.

Purpose of the Study:

• To identify genetic determinants responsible for reduced susceptibility to daptomycin in Staphylococcus aureus.
• To investigate mutations conferring daptomycin resistance in both laboratory-evolved and clinical strains.

Main Methods:

• Comparative whole-genome sequencing of daptomycin-susceptible and resistant Staphylococcus aureus strains.
• Analysis of mutations in genes encoding MprF, YycG, RpoB, and RpoC under daptomycin selective pressure.
• Sequencing of key genes (mprF, yycF, yycG, rpoB, rpoC) in clinical isolates with increased daptomycin minimum inhibitory concentrations (MICs).

Main Results:

• Accumulation of point mutations in MprF (lysylphosphatidylglycerol synthetase), YycG (histidine kinase), and RNA polymerase subunits (RpoB, RpoC) correlated with decreased daptomycin susceptibility in laboratory strains.
• Clinical isolates exhibiting treatment-emergent daptomycin resistance harbored mutations in mprF and yycG.
• Identified specific mutations in MprF and YycG as significant contributors to daptomycin resistance.

Conclusions:

• Mutations in mprF, yycG, rpoB, and rpoC are key drivers of daptomycin resistance in Staphylococcus aureus.
• These genetic alterations provide insights into daptomycin resistance mechanisms relevant to both laboratory and clinical settings.
• The identified genes represent potential targets for future therapeutic strategies to overcome daptomycin resistance.