Antibacterial activity of the essential oil of Origanum vulgare L. (Lamiaceae) against bacterial multiresistant strains isolated from nosocomial patients

Abstract

RESUMO: "Atividade antibacteriana do óleo essencial de Origanum vulgare L. (Lamiaceae) contra bactérias multiressistentes isoladas de pacientes nosocomial". Os antibióticos permanecem como a principal opção terapêutica para tratar infecções bacterianas, no entanto, existe a desvantagem de aumentarem a resistência bacteriana, e como alternativa, destaca-se a pesquisa de antimicrobianos de origem vegetal. Neste trabalho objetivou-se determinar in vitro a atividade antibacteriana do óleo essencial de Origanum vulgare L. (Lamiaceae) (orégano), sobre bactérias multirresistentes isoladas de materiais biológicos. Foram usadas 24 linhagens de bactérias de origem hospitalar, divididas em seis espécies distintas, que foram inibidas pelo óleo essencial no "screening" preliminar, realizado utilizando-se a técnica de difusão em ágar. A CIM foi determinada pelo método de microdiluição, partindo-se de soluções com as concentrações finais: 8 até 0,125% com os seguintes resultados: As quatro amostras (100%) de Escherichia coli, Enterococcus faecalis e MRSA foram inibidas pelo óleo essencial na concentração de 0,125%. Três amostras (75%) de Acinetobacter baumannii por 0,125% e uma amostra (25%) por 0,5%; Klebsiella pneumoniae (75%) por 0,125% e 25% por 0,25%; Pseudomonas aeruginosa (75%) por 0,5% e 25% por 0,25%. A CIM variou de 78 a 83%. Concluiu-se com base nos dados obtidos, que não houve diferença na concentração bactericida mínima (0,5%) do referido óleo tanto para os microrganismos Gram positivos quanto para os Gram negativos. Unitermos: Origanum vulgare, infecções bacterianas, bactérias multirresistentes.ABSTRACT: Antibiotics are considered the main therapeutic option to treat bacterial infections; however, there is the disadvantage of increasing bacterial resistance. Thus, the research of antimicrobials of plant origin has been an important alternative. This work aimed at determining the in vitro antibacterial activity of the essential oil of Origanum vulgare L. (Lamiaceae) on multiresistant bacteria isolated from biological materials. 24 strains of nosocomial bacteria were used and divided into six different species that were inhibited by the essential oil in the preliminary "screening" which was accomplished by the diffusion technique in agar. MIC was determined by the microdilution method, beginning with solutions with the final concentrations: 8 up to 0.125% with the following results: The four samples (100%) of Escherichia coli, Enterococcus faecalis and MRSA were inhibited by the essential oil at the concentration of 0.125%. Three samples (75%) of Acinetobacter baumannii at 0.125% and a sample (25%) at 0.5%; Klebsiella pneumoniae (75%) at 0.125% and 25% at 0.25%; Pseudomonas aeruginosa (75%) at 0.5% and 25% at 0.25%. MIC varied from 78 to 83%. It was concluded through the obtained data that there was not difference in the minimum bactericidal concentration (0.5%) of the referred oil for Gram positive as well for Gram negative microorganisms.

Biological properties of medicinal plants: a review of their antimicrobial activity

“…Concentrations of at least 0.125% showed higher antimicrobial efficiency on the studied bacterial strains, although P. aeruginosa was found to be more resistant to the essential oil because it was only inhibited at the concentration of 0.5% (33 (34).…”

“…The antibacterial activity of essential oils from oregano (Origanum vulgare) against multiresistant bacteria -including E. coli, E. faecalis, Acinetobacter baumannii, K. pneumoniae, P. aeruginosa and MRSA -was analyzed by Costa et al (33). Concentrations of at least 0.125% showed higher antimicrobial efficiency on the studied bacterial strains, although P. aeruginosa was found to be more resistant to the essential oil because it was only inhibited at the concentration of 0.5% (33 (34).…”

Chemical Composition and Antibacterial Activity of the Essential Oils Extracted From 4 Medicinal Plants (Labiatae) of Kerman, Iran

“…26 The leaves and flowering stems are strongly antiseptic, antispasmodic, carminative, cholagogue, diaphoretic, emmenagogue, expectorant, stimulant, stomachic, and mildly tonic. 27 The principal objective of the present study was focused on the chemical composition and antibacterial potential of essential oils of S. macrosiphon, R. officinalis, D. polychaetum, and O. vulgare against 4 bacteria causing food poisoning in human (i.e., Staphylococcus aureus, Bacillus cereus, Salmonella enterica, and Listeria monocytogenes).…”

Bee Products and Essential Oils as Alternative Agents for Treatment of Infections Caused by S. aureus

“…The antibacterial activity of essential oils from oregano (Origanum vulgare) against multiresistant bacteria, including MRSA, was analysed by Costa et al [87]. The MIC values were determined by the microdilution method.…”