Gentamicin promotes Staphylococcus aureus biofilms on silk suture

Area of Science:

• Microbiology
• Bacterial Pathogenesis
• Antimicrobial Resistance

Background:

• Bacterial biofilms on surfaces like surgical sutures pose treatment challenges.
• Biofilm-associated bacteria are often resistant to antibiotics.
• Aminoglycosides, like gentamicin, may unexpectedly promote biofilm formation.

Purpose of the Study:

• To investigate the effects of gentamicin on Staphylococcus aureus biofilms associated with silk sutures.
• To understand gentamicin's impact on biofilm viability, metabolic activity, and biomass.

Main Methods:

• S. aureus biofilms were cultured on silk sutures.
• Gentamicin susceptibility of planktonic and dispersed biofilm cells was compared.
• Intact biofilms were treated with subinhibitory and inhibitory gentamicin concentrations.
• Viability, metabolic activity, biomass, and ultrastructure were assessed.

Main Results:

• Gentamicin susceptibility was similar for planktonic and dispersed biofilm cells.
• High gentamicin concentrations did not kill bacteria in intact biofilms.
• Intact biofilms showed increased biomass and viable, metabolically active S. aureus.

Conclusions:

• Gentamicin is ineffective against S. aureus within intact suture-associated biofilms.
• Gentamicin treatment appears to promote the growth and biomass of S. aureus biofilms.