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United States Department of Agriculture

Agricultural Research Service

Research Project: MOLECULAR BIOLOGY AND GENOMICS OF FOODBORNE PATHOGENS Title: Plant derived compounds inactivate antibiotic resistant Campylobacter jejuni strains

Authors
item Ravishankar, Sadhana - VET.SCI.&MICROBI,U.OF AZ.
item Zhu, Libin - VET.SCI.&MICROBI,U.OF AZ.
item Law, Bibiana - VET.SCI.&MICROBI,U.OF AZ.
item Joens, Lynn - VET.SCI.&MICROBI,U.OF AZ.
item Friedman, Mendel

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 4, 2008
Publication Date: June 3, 2008
Citation: Ravishankar, S., Zhu, L., Law, B., Joens, L., Friedman, M. 2008 Plant derived compounds inactivate antibiotic resistant Campylobacter jejuni strains. Journal of Food Protection.71(6)1145-1149(5)

Interpretive Summary: In a collaborative study with scientists at the Department of Veterinary Science and Microbiology at the University of Arizona, Tucson, 63 Campylobacter jejuni isolates were screened for their resistance to the following widely used commercial antibiotics: ampicillin, cefaclor, ciprofloxacin, erythromycin, gentamycin, tetracycline, and trimethroprim/sulfamethoxazole. Based on this screen, two resistant and one nonresistant strain were evaluated for their susceptibility to inactivation by cinnamaldehyde and carvacrol, the main constituents of plant-derived cinnamon and oregano oils, respectively. The extent of observed inhibition of microbial growth was related to both concentration of antimicrobials and incubation time. The antimicrobial efficacy of cinnamaldehyde was greater than that of carvacrol. Our findings suggest that plant-derived compounds can inactivate at about the same rate both antibiotic-resistant and nonresistant strains of foodborne Campylobacter bacteria. These studies provide candidates for incorporation into formulations that can protect food and consumers against antibiotic resistant C. jejuni.

Technical Abstract: Sixty-three Campylobacter isolates were screened for their resistance to the antibiotics ampicillin, cefaclor, ciprofloxacin, erythromycin, gentamycin, tetracycline, and trimethroprim/sulfamethoxazole. Based on this screen, the resistant strains D28a and H2a and the nonresistant strain A24a were selected for evaluation of their susceptibility to inactivation by cinnamaldehyde and carvacrol, the main constituents of plant-derived cinnamon and oregano oils, respectively. Different concentrations (0.05, 0.1 and 0.2% v/v in sterile buffered peptone water, BPW) of cinnamaldehyde and carvacrol were added to Campylobacter cultures with initial populations of 104 CFU/ml. The samples were then mixed and incubated at 37°C. Bacteria were enumerated at incubation periods of 0, 30, 60 and 120 min. The results indicate that the extent of inhibition of microbial growth was related to both concentration of antimicrobials and incubation time and that the antimicrobial efficacy of cinnamaldehyde was greater than that of carvacrol. Both cinnamaldehyde and carvacrol exhibited rapid antimicrobial activity against both antibiotic-resistant and nonresistant Campylobacter jejuni strains at concentrations of ~0.1%. The possible significance of the results for microbiological food safety is discussed.

Last Modified: 10/24/2014
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