engleski

EDTA enhance bactericidal activity of thymol and rosemary essential oil against multiple-resistant Gram-negative bacteria

Antimicrobial activity of thymol and rosemary essential oil rich in 1.8-cineole as hydrophobic natural substances has been documented against wide range of microbes. As promising antiseptics and disinfectants with relatively high MICs, their activity could potentiate using permeabilizing action of chelators such as EDTA. Therefore, we use combination of 5 mM (1.7 mg/mL) dinatrium salt of EDTA and thymol to compare substances and their combinations against multiple-resistant nosocomial bacterial species including ESBL strains Escherichia coli (n=20), Klebsiella pneumoniae (n=11) and Pseudomonas aeruginosa (n=20), Proteus mirabilis (n=10), Salmonella enteritidis serovar Typhimurium (n=10) in late stationary faze. Standard cilinder plate and broth macrodilution method were used. With the exception of P. aeruginosa, all bacterial strains were sensitive to thymol with MIC between 2.39 and 4.06 mg/mL. The strongest enhance of bactericidal activity of thymol with EDTA were noticed in E. coli strains (p<0.0001) and P. mirabilis strains (p<0.0005). Rosemary essential oil is bactericidal against P. aeruginosa strains with MIC 11.36 vol%, and other tested bacterial species below 1.5 vol%. The addition of EDTA do not enhance activity against P. aeruginosa and P. mirabilis strains, but significantly decrease MIC against Kl. pneumoniae, and E. coli strains (p<0.05). EDTA in combination with natural biocides such as thymol or rosemary oil (with 1.8-cineole) could enhance bactericidal activity, especially against some nosocomial gram-negative bacterial strains

EDTA; thymol; rosemary oil; antimicrobial activity

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