A method for labeling specifically living and bacteria comprising the use of modified monosaccharide compounds

A method for labeling specifically living bacteria of a given category of bacteria in a sample comprising bacteria, the method comprising the steps of:

• a) incubating said bacteria of said sample with at least one modified monosaccharide compound comprising a first reactive chemical group capable to chemically react with a second reactive group, so that a monosaccharide residue bearing said first reactive group is incorporated into the polysaccharides of the outer membrane of such bacteria, especially into the LPS or CPS of the outer membrane of such bacteria, and
• b) contacting said modified monosaccharide residue incorporated within the outer membrane of the bacteria, with a labeling molecule comprising a said second reactive group, for generating the chemical reaction of said first reactive group of said monosaccharide residue incorporated within said outer membrane of said living bacteria with said second reactive group of said labeling molecule, resulting in a covalent link,
• wherein the said modified monosaccharide compound is a modified endogenous precursor of an endogenous ulosonic acid residue of the said polysaccharides of the outer membrane of said bacteria, said modified monosaccharide compound having the following formula (I), or a salt thereof:
• Wherein
• X can be O, NH or S, preferably O and NH, more preferably O, and
• R1, R2 and R3 can be independently H, OH, NH2, OH and NH2 being substituted or not by protecting groups thereof, preferably substituted by alkyl, hydroxyalkyl, acyl, formyl or imidoyl groups, and
• R4 is H or an alkyl chain in C1 to C4 each carbon being substituted or not by OH or NH2 substituted or not by protecting groups thereof, preferably by alkyl, hydroxyalkyl, acyl, formyl or imidoyl groups, and
• at least one of X, R1, R2, R3 and R4 groups being substituted by a said first reactive group.