Antibacterial Activities of Naturally Occurring Compounds against Antibiotic-Resistant Bacillus cereus Vegetative Cells and Spores, Escherichia coli, and Staphylococcus aureus

Abstract

After demonstrating the lack of effectiveness of standard antibiotics against the acquired antibiotic resistance of Bacillus cereus (NCTC 10989), Escherichia coli (NCTC 1186), and Staphylococcus aureus (ATCC 12715), we showed that the following natural substances were antibacterial against these resistant pathogens: cinnamon oil, oregano oil, thyme oil, carvacrol, (S)-perillaldehyde, 3,4-dihydroxybenzoic acid (beta-resorcylic acid), and 3,4-dihydroxyphenethylamine (dopamine). Exposure of the three pathogens to a dilution series of the test compounds showed that oregano oil was the most active substance. The oils and pure compounds exhibited exceptional activity against B. cereus vegetative cells, with oregano oil being active at nanogram per milliliter levels. In contrast, activities against B. cereus spores were very low. Activities of the test compounds were in the following approximate order: oregano oil > thyme oil approximately carvacrol > cinnamon oil > perillaldehyde > dopamine > beta-resorcylic acid. The order of susceptibilities of the pathogens to inactivation was as follows: B. cereus (vegetative) >> S. aureus approximately E. coli >> B. cereus (spores). Some of the test substances may be effective against antibiotic-resistant bacteria in foods and feeds.

Antibacterial Activities of Naturally Occurring Compounds against Mycobacterium avium subsp. paratuberculosis

“…According to a recent series of studies carried out by Friedman and colleagues, five out of the six compounds that were found to be active against M. avium subsp. paratuberculosis in this study-cinnamon oil, (14,15), while carvacrol, cinnamon oil, and oregano oil were also found to be active against antibiotic-resistant Staphylococcus aureus and Bacillus cereus vegetative cells and spores as well as against resistant Micrococcus luteus (10,11). The published MICs for the five compounds active against Campylobacter jejuni, expressed in terms of reduction of 50% of CFU, ranged from 6.6 to 190 g/ml: 430 to 1,100 g/ml for Escherichia coli O157:H7, 80 to 1,900 g/ml for Listeria monocytogenes, and 330 to 1,900 g/ml for Salmonella enterica (14,15).…”

“…The published MICs for the five compounds active against Campylobacter jejuni, expressed in terms of reduction of 50% of CFU, ranged from 6.6 to 190 g/ml: 430 to 1,100 g/ml for Escherichia coli O157:H7, 80 to 1,900 g/ml for Listeria monocytogenes, and 330 to 1,900 g/ml for Salmonella enterica (14,15). In a separate study (10), the antimicrobial activities of the test compounds carvacrol, cinnamon oil, and oregano oil were expressed as the numbers of CFU recovered from the bactericidal assay performed with different compounds compared to the number of CFU recovered from the negative control. Upon adoption of the definition of MIC from the previous studies, i.e., a 50% CFU reduction or more (as some compounds showed either no inhibition or inhibition of over 50% of the CFU at the next higher concentration), the MICs of carvacrol, cinnamon oil, and oregano oil for Staphylococcus aureus were 66.7 g/ml or above, and those for vegetative Bacillus cereus cells ranged from 0.0667 to 66.7 g/ml.…”

“…As antibiotics are associated with the development of antibiotic-resistant bacteria (35) that can pass to humans via the food chain (55), the use of antibiotics in food production is restricted and must be minimized (56). Many naturally occurring compounds, like essential oils and phenolic compounds, have been evaluated extensively for antimicrobial activity and chemically characterized (10,(12)(13)(14)(15). They are secondary plant metabolites and can be obtained naturally from different parts of plant materials of common herbs, spices, and teas, including flowers, buds, seeds, leaves, twigs, bark, wood, fruits, and roots, by steam distillation, expression, fermentation, or extraction (36) or can be synthesized.…”

The in vitro effect of Garden Thyme (Thymus vulgaris L.) extract on Brachyspira hyodysenteriae

“…Effective substances of garden thyme also affect the antibiotic-resistant microbes [23][24][25][26]; in certain cases, they might replace antibiotics [27][28][29] and might present sound alternative to growth promoters [4,30]. These joint effects improve food safety and sustainability of animal agriculture.…”

Expression, crystallization and preliminary X-ray crystallographic analysis of peptide deformylase fromCampylobacter jejuni

“…The infection mainly arises from the consumption of raw or undercooked poultry (Friedman et al, 2004). Annually, approximately 0.8 million cases of C. jejuni infection are reported, resulting in more than 8000 hospitalizations and an economic loss of about $1.5 billion in the United States (Scharff, 2012).…”