Antibiotic-resistant Staphylococcus aureus strains of swine origin: molecular typing and susceptibility to oregano (Origanum vulgare L.) essential oil and maqui (Aristotelia chilensis (Molina) Stuntz) extract.

The molecular typing and the susceptibility of Staphylococcus aureus strains of swine origin to antibiotics, oregano (Origanum vulgare L.) essential oil (EO) and Chilean blackberry maqui (Aristotelia chilensis (Molina) Stuntz) extract were determined.Twenty S. aureus strains of swine origin were subjected to molecular typing, of which six strains were selected for antimicrobial susceptibility testing. The epsilon test (Etest) was used to determine the antibiotic susceptibility. The susceptibility to natural antimicrobials (NAs): oregano EO, maqui extract, thymol (Thy) and carvacrol (Carv), was carried out using the disk diffusion method. The S. aureus strains were genetically diverse. All strains were resistant to at least one class of antibiotic, and two strains were multidrug-resistant. The minimum inhibitory concentration of oregano EO, Thy and Carv was 0·01-0·04%. Maqui extract did not show antistaphylococcal activity.Natural antimicrobials extracted from oregano have an inhibitory activity against S. aureus strains from swine origin, with no effect using maqui extract.This study provides information about the characteristics of S. aureus strains of swine origin, and about the potential use of NAs from oregano to enhance the control of antibiotic-resistant S. aureus strains in the pork supply chain.