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.

Sialic acid binding proteins, sialic acid-binding peptides and sialic acid containing oligo-saccharides are active ingredients of a novel bacterial enterotoxin neutralizer and interfere with the binding of enterotoxins, including cholera toxin, to receptors so as to exert an effect of neutralizing the toxicity, thus being utilized as an effective neutralizer and are safe and available cheaply and abundantly from by-products produced during the processing of cow's milk which renders the enterotoxin neutralizer economically advantageous for commercial use.

A keratan sulfate oligosaccharide which comprises from two to five sugar units and has sulfated N-acetylglucosamine at the reducing end and in a molecule of which at least two hydroxyl groups are sulfated, preferably, which contains at least disaccharide represented by the formula Gal(6S)-GlcNAc(6S) (in the formula, Gal, GlcN, Ac, and 6S represent a galactose, a glucosamine, an acetyl group, and a 6-O-sulfate ester, respectively) as a constitutional ingredient, and/or pharmaceutically acceptable salt thereof are used as active ingredients of anti-inflammatory agents, antiallergic agents, immunomodulators, cell differentiation inducers, and apoptosis inducers.

A composition for therapeutic or diagnostic use in regard to pathogenic microorganisms, containing as an active constituent a structural element having the formula: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are same or different and are hydrogen or an organic residue, for example lower alkyl, lower acyl, or a carbohydrate residue or an inorganic residue, such as sulphate or phosphate, and wherein OR.sub.1 is in .alpha.- or .beta.-configuration; a process for therapeutic treatment; a process for identification or quantification of the said structural element in native biological material; a process for purifying acceptor structures of bacteria; and a process for performing disinfection on surfaces.

Sialic acid binding proteins, sialic acid-binding peptides and sialic acid containing oligo-saccharides are active ingredients of a novel bacterial enterotoxin neutralizer and interfere with the binding of enterotoxins, including cholera toxin, to receptors so as to exert an effect of neutralizing the toxicity, thus being utilized as an effective neutralizer and are safe and available cheaply and abundantly from by-products produced during the processing of cow's milk which renders the enterotoxin neutralizer economically advantageous for commercial use.