# Antibacterial Activity of Clove Essential Oil (Syzygium aromaticum) Against Oxacillin-Resistant Staphylococcus pseudintermedius Isolated from Dogs with Otitis Externa

## TL;DR

Clove essential oil shows antibacterial effects against drug-resistant Staphylococcus pseudintermedius in dogs with ear infections.

## Contribution

Demonstrates clove essential oil's effectiveness against oxacillin-resistant S. pseudintermedius isolates.

## Key findings

- 34.28% of isolates were mecA-positive, and 97.14% were blaZ-positive.
- Clove oil had an average MIC and MBC of 6.4 mg/mL against both resistant and susceptible isolates.
- The oil exhibited in vitro antimicrobial activity against S. pseudintermedius.

## Abstract

Infections caused by oxacillin-resistant Staphylococcus pseudintermedius are increasingly common in veterinary medicine. The indiscriminate use of antibiotics by pet owners worsens this problem, reducing treatment efficacy and creating the need for alternative therapies. This study aimed to evaluate the inhibitory effect of clove essential oil (Syzygium aromaticum) on both oxacillin-resistant and susceptible S. pseudintermedius. Thirty-five isolates from dogs with otitis externa were analyzed. The bacteria were identified by phenotypic tests and tested for susceptibility to 22 antibiotics using disk diffusion. Resistance genes (mecA and blaZ) were detected using conventional PCR. Among the isolates, 34.28% (12/35) were positive for mecA, and 97.14% (34/35) for blaZ. The essential oil’s efficacy was assessed using broth microdilution to determine its minimum inhibitory concentration (MIC). Clove oil showed an average MIC and minimum bactericidal concentration (MBC) of 6.4 mg/mL, inhibiting both resistant and susceptible isolates. In conclusion, clove essential oil demonstrated in vitro antimicrobial activity against S. pseudintermedius.