A fluorescent in situ hybridization method for identification of a microorganism

The invention relates to fluorescent in situ hybridization (FISH) methods for identification of microorganisms. A FISH method is proposed for identification of a microorganism with at least two identically labelled oligonucleotide probes targeting different sites of rRNA of the microorganism. The method comprising the steps of (i) contacting a sample comprising a microorganism with a set of at least two identically labelled oligonucleotides under in situ hybridization conditions to produce a contacted sample with specific fluorescence of the microorganism; (ii) hybridization to two or more target sites on rRNA molecules of the microorganism; (iii) fluorescent visualization of the contacted sample to detect positive hybridization of said labelled oligonucleotides; (iv) reading and processing the contacted sample to detect fluorescence level of the hybridized microorganism.