A resistance determinant to nucleic acid-binding compounds in methicillin-resistant Staphylococcus aureus

Area of Science:

• Microbiology
• Molecular Biology
• Antimicrobial Resistance

Background:

• Methicillin-resistant Staphylococcus aureus (MRSA) is a significant global health concern.
• Recent MRSA isolates possess a plasmid conferring resistance to propamidine isethionate and cetyltrimethyl-ammonium bromide.
• The genetic basis and functional properties of this resistance determinant are not fully understood.

Purpose of the Study:

• To characterize the resistance determinant found in recent MRSA isolates.
• To determine the cationic-resistance profile of MRSA strains and their sensitive counterparts.
• To elucidate the molecular mechanism underlying this novel resistance.

Main Methods:

• Determination of minimum inhibitory concentrations (MICs) for various cationic agents.
• Preparation of cationic-resistance profiles for multiple MRSA strains and their isogenic sensitive derivatives.
• Analysis of the chemical properties of compounds targeted by the resistance determinant.

Main Results:

• The resistance determinant confers high-level resistance to propamidine isethionate and low-level resistance to cetyltrimethyl-ammonium bromide.
• MRSA strains carrying the determinant showed cross-resistance to other cationic agents, including ethidium bromide.
• All compounds associated with this resistance determinant demonstrate nucleic acid-binding properties.

Conclusions:

• A novel resistance determinant, designated NAB (nucleic acid-binding compounds)-resistance, has been identified in MRSA.
• This determinant is associated with resistance to compounds that interact with nucleic acids.
• Understanding the NAB-resistance determinant is crucial for developing strategies against emerging MRSA resistance.