Compound from Chinese medicine blocks biofilm formation on medical implant materials

S. aureus commonly forms biofilms on medical implants, causing pneumonia, meningitis, endocarditis, osteomyelitis, and bloodstream and urinary tract infections. Biofilms, which are far tougher than bacteria not incorporated into biofilms, are resistant to antibiotics even when the individual bacteria composing the biofilm lack antibiotic resistance genes. Once biofilms become attached to the surfaces of medical devices, they are extremely difficult to expunge.

PGG is "far more potent" than several other compounds found to inhibit biofilms, including IDA, NAC, and NPM, according to the report. Despite that potency, PGG did not kill S. aureus. It is also non-toxic to human epithelial and fibroblast cells. PGG likely inhibits biofilm formation during the initial attachment stage, as the investigators found PGG to be effective only when it is added to a medium within an hour after seeding. Besides polystyrene and polycarbonates, PGG inhibited biofilm formation on silicon rubber, a material commonly used in catheters, and on glass coverslips.

PGG is an active ingredient in plants that are commonly used in Chinese medicine to treat inflammation. It was one of 48 compounds purified form medicinal plants that the researchers screened for efficacy in inhibiting S. aureus biofilm formation. PGG was on sole compound from among them that did not kill the pathogens.