SPS-neutralization in tissue samples for efficacy testing of antimicrobial peptides

Area of Science:

• Microbiology
• Pharmacology
• Biochemistry

Background:

• Accurate antimicrobial efficacy testing requires neutralizing residual activity.
• Sodium polyanethol sulfonate (SPS) is a known neutralizer for aminoglycosides and polymyxins.
• This study investigates SPS's neutralization capacity for peptides, antibiotics, and disinfectants.

Purpose of the Study:

• To evaluate the efficacy of Sodium polyanethol sulfonate (SPS) in neutralizing residual antimicrobial activity.
• To determine the optimal SPS concentration for effective neutralization.
• To assess the impact of SPS neutralization on the in vitro and ex vivo efficacy testing of various antimicrobial agents.

Main Methods:

• Human skin models and ex vivo wound models were exposed to antimicrobial agents.
• Residual activity was assessed by plating on Methicillin-resistant Staphylococcus aureus (MRSA).
• Increasing concentrations of SPS were tested for neutralization efficacy against different antimicrobials.

Main Results:

• All tested antimicrobials exhibited residual activity, affecting bacterial recovery.
• SPS (≥0.05% wt/v) neutralized SAAP-148, pexiganan, and chlorhexidine, but not SSD, mupirocin, or fusidic acid.
• SPS neutralization significantly increased viable bacterial counts in efficacy tests.

Conclusions:

• Sodium polyanethol sulfonate (SPS) effectively neutralizes residual activity of SAAP-148, pexiganan, and chlorhexidine.
• This neutralization is essential to prevent the overestimation of antimicrobial efficacy.
• SPS is a valuable tool for accurate antimicrobial testing.