WASHINGTON — A small black mushroom found in the woods of northern Europe contains the first of what may be a powerful new class of antibiotics and antivirals, a researcher here says. ‘I think we are looking at a whole new world of antibiotics,’ said Michael Zasloff, M.D., Ph.D., of Georgetown University Medical Center. Plectasin, a peptide derived from a fungus called Pseudoplectania nigrella, is as effective as penicillin and vancomycin in combating experimental peritonitis and pneumonia in mice, Dr. Zasloff and colleagues reported in the Oct. 13 issue of Nature. The peptide is one of a class of molecules called defensins, which have previously been found in plants and animals. Plectasin is the first to be isolated from a fungus, Dr. Zasloff said. Plectasin was tested against a range of bacteria, including streptococcus, enterococcus, and staphylococcus, Dr. Zasloff said, but other defensins have been shown to have activity against viruses. Since about 200,000 other species of fungus exist, he said, it seems likely that many more fungal defensins will be found, possibly allowing for highly-targeted antimicrobial drugs that will render today’s broad-spectrum drugs obsolete. ‘I think we as physicians are going to see […]