The method to determine the species of bacterial strains of staphylococcus | Gdańsk University of Technology

The bacteria were classified as staphylococcus, however the doctors from MUG needed more detailed information on the species of bacteria obtained from the patient. Prof. Roman Kotłowski, D.Sc. from the Department of Molecular Biotechnology and Microbiology, Faculty of Chemistry, Gdańsk University of Technology, together with Prof. Katarzyna Garbacz, MD,Ph.D. and Ewa Kwapisz, MD, Ph.D. from the Department of Oral Microbiology at the Medical University of Gdańsk, applied an innovative method of genetic testing, enabling the bacterial species identification, defining their species as Staphylococcus succinus subsp. casei. Two strains of bacteria isolated from patients have turned out to be extremely rare nowadays. The clinical strain of staphylococcus was identified for the first time in 2006 in the Czech Republic.

An interesting fact is that the very closely related strain of Staphylococcus succinus subsp. nov. was recovered from an inclusion within a 25-35 million-year-old Dominican amber. Since it is a strain of bacteria that does not produce processing forms, it can be concluded that it owes its survival of such a long period to the amber.

A gene called nucH was studied. Although the very method of identifying bacterial species by DNA sequence analysis of the selected gene is not new, it was the first time that the sequence of the nucH gene was used as a diagnostic method to identify difficult-to-identify pathogenic staphylococcal strains. In the sequencing method, 81 pairs of nucleotides encoding almost the entire nucH gene are examined.

An alternative stage of the test may be the use of restriction enzymes specific for DNA molecules. The analysis uses enzymes that can "cut" DNA - differently for various species of bacteria. Consequently, different lengths of DNA fragments are obtained - in this case the nucH gene with a relatively short nucleotide sequence. This method is much easier than the one used so far due to the approximately 10-fold reduction in the analyzed nucleotide sequence.

– Sequencing of the identified unique nucH gene fragment seems to be a promising diagnostic test for the identification of bacterial species from the genus Staphylococcus - explains Prof. Roman Kotłowski - On the basis of our results, we can assume that probably other species of the genus Staphylococcus from different clinical samples can be identified using the sequencing method of the nucH gene fragment developed by us.

For the method to spread and be adapted to identification of other bacterial species, however, it is necessary to extend the genetic databases with a much larger number of nucH gene sequences for other staphylococci as well as other types of bacteria, and to conduct further research.