[Molecular genetic typing of methicillin-resistant Staphylococcus aureus strains, isolated in hospitals of different regions of the Russia and Belarus].

The study of the length of the amplification products of the coagulase gene with the subsequent restriction analysis (the method of PCR--restrictive fragment length polymorphism, or RFLP) was used for typing 90 S. aureus strains. Among the strains under study, 78 were methicillin-resistant S. aureus (MRSA) strains, including 74 obtained in 1986 - 2002 in hospitals of different cities of the Russia and Belarus, as well as epidemic strains EMRSA-1, -2, -3, -12, obtained from the National Laboratory of Health, London (UK). The use of this method made it possible to type all the strains under study, which were differentiated into 9 groups by means of endonuclease Sfo1 and 7 groups by means of Alu1. Majority of clinical MRSA strains, belonged, according to the type of restriction, to groups 4 and 5. The study of the coagulase gene by the method of PCR - RFLP made it possible: to analyze the epidemic situation in hospitals for a period of several years; to compare the properties of strains isolated in different hospitals; to establish the genetic relationship of strains, isolated in 1998 - 2002, with strains, isolated in 1986 - 1990. The results of the study suggest that at least two epidemic MRSA strains, genetically similar to international strains, circulate in hospitals of Russia.

[Study on the polymorphism of the coagulase gene by the method of sequencing in methicillin-resistant Staphylococcus aureus strains, isolated in hospitals in different regions of Russia and Belarus].

This method was used for typing of 31 Staphylococcus aureus methicillin-resistant (MRSA) strains; of these, 27 were clinical isolates obtained in hospitals of different cities of Russia and Belarus and 4 were international epidemic strains EMRSA-1, -2, -3, -12. The sequencing of the variable area, located in the middle part of the coagulase gene between nucleotides 979-1355 and detected with the use of information technologies, was carried out. The results of this sequencing were compared with those of the earlier study on the polymorphism of the area of the same gene between nucleotides 1513-2188, carried out by the method of PCR-restrictive fragment length polymorphism. The sequencing of the part of the coagulase gene made it possible to confirm the presence of essential differences in the nucleotide sequences of the coagulase gene in international strains EMRSA-1, -3, -12, grounds for classifying clinical isolates of MRSA strains with two groups (4 and 5), as well as the genetic relationship of different phage types, isolated in different clinics. The study revealed considerable similarity in the nucleotide composition of strains EMRSA-2 and EMRSA-12 despite the fact that, according to the results of Cfol restriction of the 3'-end, they were classified with different groups; the study also revealed the identity of the nucleotide sequences of the coagulase gene in the cultures of group 5, isolated in hospitals of Moscow, St. Petersburg, Orenburg, and strain EMRSA-2, as well as methicillin-sensitive S. aureus strain 8325-4; in addition, in clinical isolates of group 4 and strain EMRSA-1 a considerable degree of homology was revealed. The study of two different loci made it possible to find out the strain with the recombinant form of the coagulase gene. The approach used in this study permitted the differentiation of the international epidemic strains EMRSA-1, -2, -3 and -12 into individual groups, which coincided with the results of Enright et al. (2002) who used multilocus sequencing.