adherence of pathogenic bacteria having type i fimbriae to animal cells is inhibited by compositions having active constituents which are new glycopeptide and / or oligosaccharide compounds . the active constituent compounds are prepared enzymatically from vegetable flour which contains reserve glycoproteins rich in oligomannosides , preferably from a fraction enriched with soya glycoprotein 7s or with bean glycoprotein ii , although glycopeptides from ovalbumin may be utilized for the preparation of the compounds . the compounds have a polymannosidic basic structure similar to that of epithelial cells which is recognized by various pathogenic bacteria and which results in neutralizing the bacteria so they do not adhere to the cells . compositions including the active constituent compounds are effective for use in the prophylaxis , treatment and diagnosis of infectious diseases , especially those caused by coliform bacteria , and also for use in the disinfection of surfaces .