Study of the Equine Methicillin‐Resistant <i>Staphylococcus aureus</i> Bacterium With a High Ability to Form Biofilms and Changes in Its Properties Under the Influence of Farnesol

In developed countries, given the prevalence of methicillin‐resistant Staphylococcus aureus (MRSA), therapeutic options for treating such infections have become limited. In developing countries and Russia, little is known about resistance to antibiotics for St. aureus in veterinary medicine. Our research focused on (1) studying the clinical strain St. aureus from a sick horse for its ability to form a biofilm; (2) checking this clinical strain for resistance to antibiotics; (3) studying the effect of several farnesol (Far) concentrations on St. aureus biofilm; and (4) studying the effect of several Far concentrations on clinical strain resistance. The high phenotypic resistance of St. aureus isolates from a horse wound in our study highlights the importance of routine bacterial screening for inducible phenotypic resistance. This study describes for the first time the activity dynamic of the St. aureus strain in an environment containing antibacterial drugs and different concentrations of Far. Direct line revealed a correlation between strain resistance when assessed by the disk diffusion method and high ability of St. aureus strain to biofilm formation. We studied its ability to form biofilms and experimentally confirmed that Far perfectly inhibits their growth even at small concentrations from 1.6 μM/mL. St. aureus isolate showed resistance against three antibiotics out of seven. We have shown that combined treatment with antibiotics, especially in high concentrations 50–100–200 μM, increases St. aureus sensitivity to drugs.