The present invention relates to a synthetic saccharide of general formula (I) that is related to Klebsiella pneumoniae serotype O1, O2, O2ac, and O8 O-polysaccharide and carbapenem-resistant Klebsiella pneumoniae ST258 O-polysaccharide and conjugate thereof. Said synthetic saccharide, said conjugate and pharmaceutical composition containing said synthetic saccharide or said conjugate are useful for prevention and/or treatment of diseases associated with Klebsiella pneumoniae. Furthermore, the synthetic saccharide of general formula (I) is useful as marker in immunological assays for detection of antibodies against Klebsiella pneumoniae bacteria.
