Low pH nasal rinse solution enhances mupirocin antimicrobial efficacy.

Area of Science:

• Microbiology
• Pharmacology
• Otolaryngology

Background:

• Chronic rhinosinusitis (CRS) significantly impacts patient quality of life.
• Bacterial biofilms are implicated in CRS pathogenesis due to antibiotic resistance.
• Topical antibiotic delivery via nasal rinse offers localized treatment with reduced systemic effects.

Purpose of the Study:

• To investigate the efficacy of mupirocin delivered via common Australian sinus rinse solutions.
• To assess the impact of different sinus rinse formulations and pH on mupirocin's antimicrobial activity against Staphylococcus aureus.
• To determine the optimal conditions for eradicating S. aureus biofilms in the context of CRS treatment.

Main Methods:

• Evaluated planktonic and biofilm cultures of S. aureus, including methicillin-resistant (MRSA) and susceptible strains.
• Tested mupirocin efficacy in Neilmed, Flo Sinus Care, and FloCRS (at pH 5.64 and 7.7).
• Determined Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC); assessed biofilm biomass and metabolic activity.

Main Results:

• Mupirocin in low pH (5.64) FloCRS demonstrated superior efficacy against S. aureus biofilms and planktonic forms.
• Significantly greater reduction in biofilm biomass and metabolic activity was observed with mupirocin in low pH FloCRS compared to other rinses.
• The pH of the sinus rinse solution was a critical factor influencing mupirocin's antimicrobial effectiveness.

Conclusions:

• The choice of irrigant solution is critical for the antimicrobial efficacy of topical mupirocin.
• Low pH FloCRS is a promising vehicle for delivering mupirocin to eliminate S. aureus biofilms in CRS patients.
• This approach may enhance treatment outcomes for chronic rhinosinusitis by targeting persistent bacterial biofilms.