Plasmid-medicated aminoglycoside phosphotransferase of broad substrate range that phosphorylates amikacin

Area of Science:

• Microbiology
• Molecular Biology
• Antimicrobial Resistance

Background:

• Staphylococcus aureus is a significant human pathogen.
• Aminoglycoside antibiotics, like amikacin, are crucial for treating S. aureus infections.
• Emergence of antibiotic resistance necessitates continuous surveillance.

Purpose of the Study:

• To identify and characterize novel resistance mechanisms in clinical isolates of Staphylococcus aureus.
• To investigate the presence and function of aminoglycoside-modifying enzymes.

Main Methods:

• Detection of plasmid-mediated genes in clinical S. aureus isolates.
• Enzymatic assays to determine the substrate specificity of identified phosphotransferases.
• Phenotypic testing to assess amikacin susceptibility.

Main Results:

• A plasmid-mediated aminoglycoside phosphotransferase (APH) capable of phosphorylating amikacin was identified.
• The presence of this APH enzyme did not result in a detectable level of amikacin resistance in the studied S. aureus strains.
• The enzyme's activity suggests a potential role in modifying amikacin, but not conferring clinical resistance.

Conclusions:

• A novel amikacin-phosphorylating enzyme exists in clinical Staphylococcus aureus.
• This enzyme does not confer amikacin resistance, indicating other resistance mechanisms may be more dominant or the enzyme's role is subtle.
• Further research is needed to elucidate the precise role and impact of this enzyme in S. aureus pathogenesis and resistance.