Antibacterial Effect of the In Vitro Interaction Between Clotrimazole and Chlorhexidine Against Staphylococcus...

Area of Science:

• Veterinary Dermatology
• Antimicrobial Resistance
• Infectious Diseases

Background:

• Staphylococcus pseudintermedius is a primary cause of canine pyoderma.
• Increasing multidrug resistance necessitates alternative treatments.
• Topical antimicrobial combinations like chlorhexidine (CHX) and clotrimazole (CLT) are gaining attention.

Purpose of the Study:

• Evaluate the in vitro antibacterial activity of a 2:1 CHX-CLT combination.
• Assess the pharmacological interaction between CHX and CLT against S. pseudintermedius.

Main Methods:

• Sixteen S. pseudintermedius isolates from canine pyoderma were identified.
• Methicillin resistance was confirmed genotypically (mecA) and phenotypically.
• Minimum Inhibitory Concentrations (MICs) were determined using broth microdilution.
• Fractional Inhibitory Concentration Index (FICI) was calculated to assess drug interaction.

Main Results:

• All isolates harbored mecA; 25% showed phenotypic oxacillin resistance.
• The 2:1 CHX-CLT combination significantly reduced MICs compared to individual agents.
• MICs for the combination ranged from 0.39-0.781 µg/mL for CHX and 0.195-0.39 µg/mL for CLT.
• Drug interaction was additive in 81.25% of isolates.

Conclusions:

• The CHX-CLT combination exhibits enhanced in vitro antibacterial activity against S. pseudintermedius.
• Predominantly additive interactions were observed, supporting synergistic effects.
• Results advocate for CHX-CLT topical formulations as a viable therapeutic option for canine pyoderma, addressing antimicrobial resistance.