Spices are Antimicrobial and Inhibit Biofilms
Phytochemicals Block Quorum Sensing and Stop Antibiotic Resistance
Particular herbs and spices are associated with each of the world's many distinctive cuisines. There appears to be a natural pairing of spices with geography and climate. Most people just eat up and enjoy. Those who look beyond their plates to examine the interplay between the human pathogens lurking in the food and the omnipresent accompanying spices, discover the power of phytochemistry. Plants have adapted to their bacterial pathogens by producing antibiotic phytochemicals. Moreover, some phytochemicals can stop the formation of the complex bacterial communities called biofilms.
A Spice for Every Pathogen -- Phytochemicals Are Natural Antibiotics
More than a decade ago, Paul Sherman at Cornell University began to notice geographic patterns in spice usage. In his travels, he tested local herbs and spices as antibiotics against local human pathogenic bacteria. Local spices killed local bacteria, but other combinations weren't always effective. It appeared that over time cuisine was optimized for dining safety. Spices are natural antibiotics.
Beyond Natural Antibiotics: Blocking Bacterial Communication
As the lifestyles of human bacterial pathogens were examined, it was observed that some pathogens were able to tolerate antibiotic drugs by forming complex colonies with other species of bacteria, i.e. biofilms. Antibiotics were effective against scattered bacteria, but couldn't touch bacteria sequestered in the center of a bacterial community. Biofilms protect pathogens.
Phytochemicals are Quorum Sensing Inhibitors
Many of the drugs now commonly used in medicine were first identified as active ingredients in plant extracts, i.e. phytochemicals. Plants are adept at producing a wide array of chemicals with refined abilities to block bacterial functions. So when researchers sought chemicals to solve the problem of pathogens forming biofilms, it was natural to test plant extracts for inhibiting compounds. In a recent article (Fitoterapia 78 (2007) 302-310), D.A. Vattem et al. added extracts from dietary berries, herbs and spices to bacterial pathogens, including the toxin producing Escherichia coli (EC)O157:H7, and checked for the ability to produce a chemical that signals the formation of a biofilm. The effective phytochemicals inhibited the bacteria from recognizing a critical density of bacteria, i.e. quorum sensing, and responding with the production of the biofilm-triggering chemical.
Spices Inhibit Biofilms and Quorum Sensing Inhibitors Are Common in Dietary Berries and Herbs
Blueberry, raspberry, cranberry, blackberry and strawberry extracts were effective as quorum sensing inhibitors (QSIs). Common herbs such as oregano, basil, rosemary and thyme were also effective. Turmeric, ginger and kale were also tested and found to contain QSIs.
Resistance Factors Are Mobilized by Quorum Sensing
Many of the pathogenic characteristics of bacteria are activated by quorum sensing triggers. Common phytochemicals can block quorum sensing and thereby reduce the exchange of antibiotic resistance plasmids between normal gut flora and pathogens. It may make sense, in the absence of other prohibitions, to eat food with many different spices before a course of antibiotics. The spices should make the pathogens more vulnerable and prevent any exchange of genes that may lead to a future problem.
Spices block quorum sensing
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