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Garlic blocks quorum sensing and promotes rapid clearing of pulmonary Pseudomonas aeruginosa infections
Thomas Bjarnsholt1, Peter �strup Jensen2, Thomas B. Rasmussen1, Lars Christophersen2, Henrik Calum2, Morten Hentzer3, Hans-Petter Hougen4, J�rgen Rygaard5, Claus Moser2, Leo Eberl6, Niels H�iby2 and Michael Givskov1

The opportunistic human pathogen Pseudomonas aeruginosa is the predominant micro-organism of chronic lung infections in cystic fibrosis patients. P. aeruginosa colonizes the lungs by forming biofilm microcolonies throughout the lung. Quorum sensing (QS) renders the biofilm bacteria highly tolerant to otherwise lethal doses of antibiotics, and protects against the bactericidal activity of polymorphonuclear leukocytes (PMNs). It has been previously demonstrated that QS is inhibited by garlic extract. In this study, the synergistic effects of garlic and tobramycin, and PMNs activities have been evaluated. P. aeruginosa was grown in vitro in continuous-culture once-through flow chambers with and without garlic extract. The garlic-treated biofilms were susceptible to both tobramycin and PMN grazing. Furthermore, the PMNs showed an increase in respiratory burst activation, when incubated with the garlic-treated biofilm. Garlic extract was administered as treatment for a mouse pulmonary infection model. Mice were treated with garlic extract or placebo for 7 days, with the initial 2 days being prophylactic before P. aeruginosa was instilled in the left lung of the mice. Bacteriology, mortality, histopathology and cytokine production were used as indicators. The garlic treatment initially provoked a higher degree of inflammation, and significantly improved clearing of the infecting bacteria. The results indicate that a QS-inhibitory extract of garlic renders P. aeruginosa sensitive to tobramycin, respiratory burst and phagocytosis by PMNs, as well as leading to an improved outcome of pulmonary infections.

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Effects of Fresh Garlic Extract on Candida albicans BiofilmsJennifer A. Shuford, James M. Steckelberg, and Robin Patel* The effects of fresh garlic extract (FGE) against planktonic Candida spp. have been demonstrated in vitro and have been attributed to the action of allicin (3), a sulfur-containing compound that is formed at levels of approximately 3 to 5 mg/g of fresh clove (8). Biofilm-associated, or sessile, Candida albicans organisms demonstrate increased resistance to traditional antifungal agents that have activity against their planktonic counterparts (5). Therefore, we investigated the activity of FGE against both planktonic and sessile forms of C. albicans.

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0411 Garlic Allicin as a Means to Control Oral Pathogens A. JAMIL1, D. STEINBERG1, Z. LUDMER2, T. GOLAN2, R. NAOR1, and G. BACHRACH1, 1Hebrew University Hadassah, Jerusalem, Israel, 2Hebrew University, Rhovot, IsraelIntroduction: Periodontal disease is a chronic bacterial infection that affects the gums and bone supporting the teeth. Porphyromonas gingivalis is a Gram-negative anaerobe that is implicated as the major etiologic agent of adult periodontitis. P. gingivalis produces cysteine proteinases termed gingipains, in cell-associated and secretory forms. Gingipains consist of arginine-X-specific proteinases (Arg-gingipains, Rgps) and lysine-X-specific proteinase (Lys-gingipain, Kgsp). Previous studies using various P. gingivalis mutants deficient in the Rgp- and/or Kgp-encoding genes revealed that these enzymes are important for the bacterium's virulence and survival in the periodontal pockets. Thus, development of gingipains inhibitors provides new therapeutic approaches to treat periodontal diseases. Herbal extracts have been used as therapeutic agents throughout the human history. Allicin is a powerful medicinal compound derived from garlic and provides reputed health benefits. Aim: In this study the potential of a unique garlic allicin extract was tested as a means to control oral pathogens. Materials and Methods: Allicin was extracted from garlic and stabilized by solvent extraction. Bacterial growth inhibition by allicin was determined using the broth dilution method. Allicin's antiproteolytic activity was determined using nondenaturing SDS-polyacrylamid gel zymography and by using the chromogenic substrate N-benzoyl -L-Arg-p-nitroanilide(pNA). Streptococcus mutans biofilm inhibition and killing was determined using live dead staining followed by confocal laser scanning microscopy. Results: 1- Allicin was found to inhibit growth of all tested bacteria (P. gingivalis, Fusobacterium nucleatum, Actinobacillus (Aggregatibacter) actinomycetemcomitans, Streptococcus mutans, S. sobrainus, Escherichia coli, and Actinomyces viscosus). 2 - Allicin was found to be a potent irreversible inhibitor of the P. gingivalis proteases. 3- Allicin was found capable of killing S.mutans growth in biofilm. Conclusion: Our results suggest that our Garlic allicin extract has a potential use for prevention and treatment of periodontal disease.

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