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Department of Biomedical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, Massachusetts (M.D.K., N.B.); Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio (N.V.A., M.S.); Institute of Infectious Diseases and Public Health, University of Ancona, Ancona, Italy (O.C., A.G., C.S., G.S.); Department of General Surgery, Instituto Nazionale Riposo e Cura Anziani/Instituto de Ricovero e Cura a Carattere Scientifico (INRCA IRRCS), University of Ancona, Ancona, Italy (R.G., V.S.); and Experimental Animal Models for Aging Units, Research Department, INRCA IRRCS, Ancona, Italy (F.O.)
Staphylococci are a major health threat because of increasing resistance to antibiotics. An alternative to antibiotic treatment is preventing virulence by inhibition of bacterial cell-to-cell communication using the quorum-sensing inhibitor RNAIII-inhibiting peptide (RIP). In this work, we identified 2',5-di-O-galloyl-D-hamamelose (hamamelitannin) as a nonpeptide analog of RIP by virtual screening of a RIP-based pharmacophore against a database of commercially available small-molecule compounds. Hamamelitannin is a natural product found in the bark of Hamamelis virginiana (witch hazel), and it has no effect on staphylococcal growth in vitro; but like RIP, it does inhibit the quorum-sensing regulator RNAIII. In a rat graft model, hamamelitannin prevented device-associated infections in vivo, including infections caused by methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis strains. These findings suggest that hamamelitannin may be used as a suppressor to staphylococcal infections.
Address correspondence to: Dr. Naomi Balaban, Department of Biomedical Sciences, Cummings School of Veterinary Medicine, Tufts University, 200 Westboro Rd., North Grafton, MA 01536. E-mail: naomi.balaban{at}tufts.edu