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Antimicrobial effect and mode of action of terpeneless cold-pressed Valencia orange essential oil on methicillin-resistant Staphylococcus aureus.

ABSTRACT: The objectives of this study were to evaluate the antistaphylococcal effect and elucidate the mechanism of action of orange essential oil against antibiotic-resistant Staphylococcus aureus strains.The inhibitory effect of commercial orange essential oil (EO) against six Staph. aureus strains was tested using disc diffusion and agar dilution methods. The mechanism of EO action on MRSA was analysed by transcriptional profiling. Morphological changes of EO-treated Staph. aureus were examined using transmission electron microscopy. Results showed that 0·1% of terpeneless cold-pressed Valencia orange oil (CPV) induced the cell wall stress stimulon consistent with the inhibition of cell wall synthesis. Transmission electron microscopic observation revealed cell lysis and suggested a cell wall lysis-related mechanism of CPV.CPV inhibits the growth of Staph. aureus, causes gene expression changes consistent with the inhibition of cell wall synthesis, and triggers cell lysis.Multiple antibiotics resistance is becoming a serious problem in the management of Staph. aureus infections. In this study, the altered expression of cell wall-associated genes and subsequent cell lysis in MRSA caused by CPV suggest that it may be a potential antimicrobial agent to control antibiotic-resistant Staph. aureus.

SUBMITTER: Muthaiyan A

PROVIDER: S-EPMC3324624 | biostudies-literature | 2012 May

REPOSITORIES: biostudies-literature

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Antimicrobial effect and mode of action of terpeneless cold-pressed Valencia orange essential oil on methicillin-resistant Staphylococcus aureus.

Muthaiyan A A Martin E M EM Natesan S S Crandall P G PG Wilkinson B J BJ Ricke S C SC

Journal of applied microbiology 20120320 5

<h4>Aims</h4>The objectives of this study were to evaluate the antistaphylococcal effect and elucidate the mechanism of action of orange essential oil against antibiotic-resistant Staphylococcus aureus strains.<h4>Methods and results</h4>The inhibitory effect of commercial orange essential oil (EO) against six Staph. aureus strains was tested using disc diffusion and agar dilution methods. The mechanism of EO action on MRSA was analysed by transcriptional profiling. Morphological changes of EO-t ...[more]

PMID: 22372962

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Project description:Staphylococcus aureus has been recognized as an important cause of human disease for more than 100 years. Resistance to multiple classes of antibiotics is becoming an increasingly difficult problem in the management of methicillin-resistant S. aureus (MRSA) and vancomycin-intermediate resistant S. aureus (VISA) infections. One approach to the MRSA and VISA problem, involves the discovery and development of new natural antimicrobials. The antimicrobial properties of essential oils of plant origin have been recognized for many years. In this study 0.1% of commercial cold pressed terpeneless Valencia orange oil (CPV) showed inhibitory and lytic activity against MRSA and VISA. To identify the mechanisms of action of CPV genomic response of CPV treated MRSA was analyzed by transcriptional profiling. Results showed alteration in the expression of cell wall peptidoglycan biosynthesis associated genes in the CPV treated cells. Transmission electron microscopic observation of CPV treated MRSA cells exhibited cell wall damage and cell lysis. Overall results of this study suggest that CPV may be a potential anti-staphylococcal agent for MRSA. Overnight grown S. aureus COL was inoculated in TSB medium (20 ml) in a 50 ml Erlenmeyer flask and incubated at 37°C, with shaking at 200 rpm. Growth was measured at regular intervals at 600 nm until OD reached approximately 0.4. Based on the GIC study ½ x MIC concentration of EO was added for 15 min of challenge. Control cultures were not challenged with EO and were also incubated for 15 min. Total bacterial RNA was isolated as previously described and the RNA samples were then converted to fluorescently-labeled cDNA and hybridized to S. aureus microarrays version 6 (NIAID's Pathogen Functional Genomics Resource Center). Hybridization signals were scanned using an Axon4000B scanner (Molecular Devices, Sunnyvale, CA ) with Acuity 6.0 software and scans were saved as TIFF image. Scans were analyzed using TIGR-Spotfinder (www.tigr.org/software/) software and the local background was subsequently subtracted. The data set was normalized by applying the LOWESS algorithm using TIGR-MIDAS (www.tigr.org/software/) software. The normalized log2 ratio of test/reference signal for each spot was recorded. Genes with less than three data points were considered unreliable, and their data points were discarded. The averaged log2 ratios for each remaining gene on the 6 replicate slides were ultimately calculated. Significant changes of gene expression were identified with SAM (significance analysis of microarrays; www.tat.stanford.edu/~tibs/SAM/index.html. Contents of raw data files: Channel A = Cy3 dye Channel B = Cy5 dye

Project description:BackgroundThe increasing emergence of multidrug-resistant Gram-positive bacterial infections necessitates new antibacterial agents with novel mechanisms of action that can be used to treat these infections. Lomitapide has been approved by FDA for years in reducing levels of low-density lipoprotein (LDL) in cases of familial hypercholesterolemia, whereas the antibacterial effect of lomitapide remains elusive. In this study, the inhibitory activities of lomitapide against Gram-positive bacteria were the first time explored. Quantitative proteomics analysis was then applied to investigate the mechanisms of action of lomitapide.ResultsThe minimum inhibitory concentration (MIC) values of lomitapide against Gram-positive bacteria including both methicillin sensitive and resistant Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Enterococcus faecium, and Streptococcus agalactiae were range 12.5-50 μM. Moreover, lomitapide also inhibited anti-biofilm activity against clinical S. aureus isolates. A total of 106 proteins with > 1.5-fold changes in expression were identified upon 1/2 × MIC lomitapide exposure, including 83 up-regulated proteins and 23 down-regulated proteins. Based on bioinformatics analysis, the expression of cell wall damage response proteins including two-component system VraS/VraR, lipoteichoic acid (LPA) D-alanylnation related proteins D-alanyl carrier protein (dltC) and carrier protein ligase (dltA), methionine sulfoxide reductases (mrsA1 and mrsB) were up-regulated. Moreover, the expression of SaeS and multiple fibrinogen-binding proteins (SAOUHSC_01110, FnBPB, SAOUHSC_02802, SdrC, SdrD) which were involved in the bacterial adhesion and biofilm formation, was inhibited by lomitapide. Furthermore, VraS/VraR deletion mutant (ΔvraSR) showed an enhanced lomitapide sensitivity phenotype.ConclusionLomitapide displayed broad antimicrobial activities against Gram-positive bacteria. The antibacterial effect of lomitapide may be caused by cell wall destruction, while the anti-biofilm activity may be related to the inhibition of surface proteins.

Dataset Information

Antimicrobial effect and mode of action of terpeneless cold-pressed Valencia orange essential oil on methicillin-resistant Staphylococcus aureus.

Publications

Antimicrobial effect and mode of action of terpeneless cold-pressed Valencia orange essential oil on methicillin-resistant Staphylococcus aureus.

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