Garlic Outperforms Antibiotics in Key Function, Study Finds

A compound commonly found in garlic kills Campylobacter jejuni, one of the most common causes of foodborne illness, better than antibiotics, according to researchers at Washington State University in Pullman.

Some 2.4 million Americans develop Campylobacter every year, most after eating raw or undercooked poultry or foods cross-contaminated by preparation near poultry. “A year or so ago, we found that a garlic-derived compound called diallyl sulfide can kill Campylobacter in culture,” said Michael Konkel, PhD, a professor in WSU’s School of Molecular Biosciences and a co-investigator on the study.

In the new paper, Dr. Konkel and his post-doctoral researcher, Xiaonan Lu, PhD, tested the garlic derivative’s ability to wipe out Campylobacter in the more resistant, real-world milieu of a biofilm, where the pathogen is about 1,000 times more resistant to antibiotics. Their findings: The compound easily penetrated the biofilm and combined with a sulfur-containing enzyme. “It causes bacteriolysis: Essentially, the bacteria explode.”

Dr. Lu, the study’s first author, and Dr. Konkel reported that diallyl sulfide was as effective against Campylobacter as 100 times as much of the antibiotics erythromycin and ciprofloxacin, and worked much more quickly. Dr. Konkel noted that their previous work has found that the same compound is also effective against other pathogens, including Listeria monocytogenes and Escherichia coli O157:H7.

It wouldn’t be hard to test this approach at the industry level, Dr. Konkel believes. “It’s a commercially available compound already; a lot of people use it in science to look at how it kills bacteria, but I don’t know if it’s being used more broadly in the marketplace,” he said. “People will still have to test it in the real world to see if it is effective, but that’s a logical next step and probably quite easy to do.”

In addition to its potential use in food processing plants, Dr. Konkel suggested that diallyl sulfide might be a useful alternative to sanitizing chemicals like chlorine that are used in commercial kitchens, delis, and hot-food bars. “The amount of the compound we’re using is very small, and, of course, it’s already found in food,” he said. “So it should not pose any health risk to people.”

The study was published in the May 1 edition of the Journal of Antimicrobial Chemotherapy.

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