Carvacrol and Cinnamaldehyde Inactivate Antibiotic-Resistant Salmonella enterica in Buffer and on Celery and Oysters

Abstract

The emergence of antibiotic-resistant Salmonella is of concern to food processors. The objective of this research was to identify antimicrobial activities of cinnamaldehyde and carvacrol against antibiotic-resistant Salmonella enterica in phosphate-buffered saline (PBS) and on celery and oysters. Twenty-three isolates were screened for resistance to seven antibiotics. Two resistant and two susceptible strains were chosen for the study. S. enterica cultures (10(5) CFU/ml) were added to different concentrations of cinnamaldehyde and carvacrol (0.1, 0.2, 0.3, and 0.4% [vol/vol]) in PBS, mixed, and incubated at 37 degrees C. Samples were taken at 0, 1, 5, and 24 h for enumeration. Celery and oysters were inoculated with S. enterica (10(6-7) CFU/ml), treated with 1% cinnamaldehyde or 1% carvacrol, incubated at 4 degrees C, and then sampled for enumeration on days 0 and 3. Both antimicrobials induced complete inactivation of S. enterica in PBS at 0.3 and 0.4% on exposure, and on 0.2% in 1 h. Exposure to cinnamaldehyde at 0.1% inactivated all pathogens at 1 h, and survivors were observed only for Salmonella Newport with 0.1% carvacrol at 1 h. In celery, 1% carvacrol reduced S. enterica populations to below detection on day 0, while 1% cinnamaldehyde reduced populations by 1 and 2.3 log on day 0 and day 3, respectively. In oysters, both antimicrobials caused about 5-log reductions on day 3. These results show the potential antimicrobial effects of carvacrol and cinnamaldehyde against antibiotic-resistant S. enterica in vitro and in foods.

Salmonella Heidelberg Strain Responses to Essential Oil Components

“…The antimicrobial effect of EOs has been reported to be concentration dependent (Sivropoulou et al 1996). Ravishankar et al (2010) reported that at a 0.2% concentration, antimicrobials, carvacrol and cinnamaldehyde completely inactivated the antibiotic-resistant and -susceptible isolates of S. enterica. Zhou et al combination against S. Typhimurium, and reported the lowest concentrations of cinnamaldehyde, thymol and carvacrol inhibiting the growth of S. Typhimurium significantly were 200, 400 and 400 mg/L, respectively.…”

Hydrosol of Thymbra capitata Is a Highly Efficient Biocide against Salmonella enterica Serovar Typhimurium Biofilms

“…The main constituent of the T. capitata hydrosol is carvacrol, with a concentration of 943.6 mg/liter (0.0943%). Several studies have demonstrated that carvacrol has both bacteriostatic and bactericidal activity against foodborne microorganisms, including Salmonella enterica (27,(73)(74)(75). The effectiveness of carvacrol as a natural antimicrobial compound is well established, and its mechanism of action is believed to be associated with structural and functional damage to cellular membranes (25,28,(75)(76)(77).…”

Combining essential oils and olive extract for control of multi-drug resistant Salmonella enterica on organic leafy greens

“…This strain is resistant to amoxicillin-clavulanic acid, ampicillin, cefoxitin, chloramphenicol, streptomycin, and tetracycline (Ravishankar et al 2010). Stock culture of the organism was maintained in cryovials (Microbank TM Austin, TX, USA.)…”

“…Moore-Neibel et al (2013) found that oregano oil was effective against S. Newport on organic leafy greens and Ravishankar et al (2010) found that cinnamaldehyde, the antimicrobial component in cinnamon leaf oil, and carvacrol, inactivated Salmonella serovars in vitro and S. Newport on celery and oysters.…”