Levamisole as a Strategy Against Bacteria from Canine Otitis Externa: An In Vitro Evaluation.

Area of Science:

• Veterinary Medicine
• Microbiology
• Pharmacology

Background:

• Canine otitis externa is common and can lead to multidrug-resistant infections.
• Inadequate treatment of canine otitis externa contributes to antimicrobial resistance.
• Drug repurposing offers a novel strategy for managing this prevalent condition.

Purpose of the Study:

• To evaluate the antimicrobial and antibiofilm properties of levamisole against bacterial isolates from canine otitis externa.
• To assess levamisole's impact on bacterial biofilm formation and dynamics over 120 hours.

Main Methods:

• Tested 50 clinical bacterial isolates from dogs with otitis externa.
• Determined minimum inhibitory concentration (MIC) for planktonic bacteria.
• Assessed activity against mature biofilms using minimum biofilm eradication concentration (MBEC).
• Evaluated levamisole's effect on biofilm formation at various concentrations over 120 hours.

Main Results:

• Levamisole exhibited MICs ranging from 0.58 to 2.34 mg/mL.
• Reduced mature biofilm biomass significantly (p < 0.05) with MBEC values from 1.17 to 18.75 mg/mL.
• Significantly inhibited biofilm formation at the MIC (1.17 mg/mL) for all isolates over 120 hours (p < 0.05).

Conclusions:

• Levamisole possesses significant antimicrobial and antibiofilm activity against bacteria implicated in canine otitis externa.
• Levamisole demonstrates potential as a preventive therapeutic agent for biofilm-associated canine otitis externa.
• Drug repurposing levamisole is a viable strategy for managing multidrug-resistant bacterial infections in canine otitis externa.