Identification of microorganisms from pure culture in less than 5 minutes

By Christelle Raffin, Eurofins Laboratoire Microbiologie Ouest, France

Traditional bacterial identification is based on the analysis of phenotypic characteristics after the growth of the organism to be identified under different conditions. The result is thus obtained 24 hours after isolation of the strain at the earliest. Furthermore, with current methods the identification may be ambiguous and in some cases leaves doubt as to the nature of the bacteria. In case of failure of the traditional identification, analysis using molecular biology techniques of the specific sequencing of the 16S rRNA is of value but is expensive to carry out.

In recent years, automatic analytical systems using mass spectrometry such as MALDI-TOF have revolutionised bacterial identification in the medical sector. This ingenious method based on protein analysis provides a spectrum which is a kind of bar code specific to each organism analysed. The identification of the microorganism is performed by comparing the pattern obtained with a validated database. In order to have high reliability in the identification, the laboratory needs a reference database of recorded spectra for the organisms of interest. Available databases can be customised and completed by introducing new spectra, e.g. for specific bacteria.

Using this equipment and linked to databases, accurate and reliable test results can be obtained in less than five minutes for a given colony. The MALDI -TOF system can identify bacteria, yeast and moulds, regardless of their origin (food, environmental or clinical samples).

Several laboratories in the Eurofins Group have invested in this technology in order to adapt it to a food context. Currently available databases allow more than 2500 different species of microorganisms to be distinguished including Enterobacteriaceae, Staphylococci, Streptococci, Anaerobic bacteria, Candida, Aspergillus and Penicillium, and are updated regularly with strains detected in Eurofins laboratories. This now enables Eurofins customers to have bacterial identifications carried out rapidly and to improve their risk management and control of the flora present in their products.

Contact: Your local Eurofins laboratory or AsmElmo@eurofins.com