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Analysis of methicillin resistant Staphylococcus aureus strains from Czech Republic and Slovakia
Brajerová, Marie ; Tkadlec, Jan (advisor) ; Karpíšková, Renáta (referee)
Methicillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen that has spread into the community since the 90s. In general, the community-associated (CA- MRSA) strains are more virulent, but less resistant to antimicrobials than the hospital- acquired strains (HA-MRSA). Some lineages of MRSA such as sequence type 8 have been transmitted more successfully around the world than others and there are situations where a dominant lineage has been replaced by a new one. The factors that are crucial for the selection of dominant lineage are often not clear. As part of this thesis, a longitudinal study of MRSA epidemiology in the Motol University Hospital during the period of 2018-2020 was performed and the occurrence of MRSA clonal complexes was characterized. A multicenter study of the epidemiological situation of MRSA in Slovakia during the period of January - April 2020 was also performed concomitantly. Moreover, several isolates from dominant lineages were further characterized by their phenotype. In the Motol University Hospital study, it was found that the HA-MRSA of the clonal complex 5 dominates and is represented mainly by spa-type t586; a finding that concurs with recent studies from the Czech Republic. In Slovakia, similar to the Czech Republic, MRSA lineages from clonal...
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SCCmec and other mobile genetic elements associated with methicillin resistance in staphylococci.
Kubištová, Lucie ; Lichá, Irena (advisor) ; Plocek, Vítězslav (referee)
Staphylococci are common part of human flora but also they are a dangerous pathogen. Among staphylococci strains, methicillin resistance is widespread. The mecA gene, organized in mec complex, is responsible for methicillin resistance. The mec complex is part of mobile genetic element - staphylococcal chromosome cassette SCCmec. SCCmec is large variable mobile genetic element and it is always composed of three parts - mec complex, ccr complex and J regions. Complex mec consists of mecA gene and its regulatory genes mecR1 and mecI. Complex ccr encodes recombinase genes, they are responsible for excision and insertion of SCCmec. J regions are remaining parts of SCCmec, which include other mobile genetic elements that directly influence methicillin resistance genes expression or carry genes for resistance to other antimicrobial agents. SCCmec or its parts can be transferred by horizontal gene transfer between staphylococci both intraspecific and interspecific, although mechanism of its transfer is still unknown. Eleven types of SCCmec have been described so far. In this thesis, I summarized the findings about molecular composition of SCCmec, horizontal gene transfer of the genes encoding methicillin resistance and molecular evolution of SCCmec. Mobile genetic elements play a key role in evolution and...
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