Antibacterial and anti-biofilm potential of Plectranthus amboinicus (Lour.) Spreng essential oil and Carvacrol against Staphylococcus aureus and Escherichia coli

Introduction: S. aureus and E. coli are pathogen that can cause persistent infections due to antibiotic resistance mechanisms and to its ability to adhere and form biofilm.The search for new agents from natural resources to counter microbial biofilm is an urgent priority in healthcare. Objetive: Chemical composition and antibacterial and anti-biofilm activity of Plectranthus amboinicus essential oil (PAEO) and of carvacrol were investigated against Escherichia coli and Staphylococcus aureus. Methodology: PAEO chemical analysis was performed by gas chromatography coupled to a mass spectrometer. Antimicrobial activity was assessed by disc diffusion method and broth microdilution method to determine minimum inhibitory concentrations (MICs). Antibiofilm activities were investigated using 96-well plates with crystal violet assay. Results: Carvacrol (85.25%) was the major component in the PAEO. According to disc diffusion test the ability of PAEO and carvacrol for inhibition of bacteria in planktonic form was confirmed. Minimum inhibitory concentration (MIC) of PAEO for S. aureus and E. coli were 0.31 and 1.25%, respectively, with bactericidal effect. Carvacrol demonstrated a significant antibacterial property (MIC = 0.31%), exhibiting bacteriostatic effect against S. aureus and bactericidal effect against E. coli. Carvacrol significantly inhibited the formation of E. coli biofilm (58.9%). Moreover, carvacrol inactivated a mature biofilm. Conclusion: The data obtained are promising, making it possible to develop new therapeutic alternatives. These results denote the potentiality of carvacrol as a source for the treatment of diseases caused by E. coli and S. aureus.Introduction: Staphylococcus aureus and Escherichia coli are pathogens that cause chronic infections due to antibiotic resistance mechanisms and their ability to adhere to surfaces and to form biofilms. The search for new agents from natural resources to counter microbial biofilms is an urgent priority in healthcare. Objetive: chemical composition, antibacterial and anti-biofilm activity of Plectranthus amboinicus essential oil (PAEO) and carvacrol were investigated against E. coli and S. aureus. Methodology: PAEO was chemically analyzed using gas chromatography coupled to a mass spectrometer. Antimicrobial activity was assessed by the disc diffusion method and broth microdilution method to determine minimum inhibitory concentrations (MICs). Antibiofilm activity was investigated using 96-well plates with a crystal violet assay. Results: carvacrol (85.25%) was the major component of PAEO. The disc diffusion test confirmed the ability of PAEO and carvacrol in inhibiting bacteria in their planktonic form. The MICs of PAEO against S. aureus and E. coli were 0.31 and 1.25%, respectively, with bactericidal effect. Carvacrol demonstrated a significant antibacterial property (MIC = 0.31%), exhibiting bacteriostatic effects against S. aureus and bactericidal effects against E. coli. Carvacrol considerably inhibited E. coli biofilm formations (58.9%). Moreover, carvacrol inactivated the mature biofilms. Conclusion: the data obtained are promising, and facilitates the development of new therapeutic alternatives. These results indicate the potential of carvacrol in treating diseases caused by E. coli and S. aureus