Publication details

Transduction of antibiotic resistance plasmids in methicillin resistant <I>Staphylococcus aureus</I> strains



Year of publication 2008
Type Article in Proceedings
Conference 13th International Symposium on Staphylococci and Staphylococcal Infections
MU Faculty or unit

Faculty of Science

Field Genetics and molecular biology
Keywords Staphylococcus aureus; bacteriophages; plasmid transduction; horizontal gene transfer
Description Objective: Most of horizontal gene transfer in S. aureus is dependent on bacteriophages which, therefore, play an important role in the evolution of this species. Transfer of virulence and antibiotic resistance genes by phages occurs by lysogenic conversion and/or by transduction. Our work was focused on generalized transduction of resistance plasmids in MRSA strains. Methods: The plasmid content was estimated in a set of 66 clinical MRSA strains. Three strains harboring tetracycline and penicillinase plasmids were chosen as the donor strains. The plasmid transduction was performed by transducing phages phi53 and 80alpha into prophage-less strains 8325-4 and 1039, restriction-deficient strain SA113, and into clinical MRSA strains used as recipients. Further, we tested transducing capability of prophages induced by UV-light from plasmid-positive lysogenic MRSA strains. Results: Both penicillinase (36.7, 30.2 and 28 kb) and tetracycline (4.0 and 4.4 kb) resistance plasmids were successfully transferred from the MRSA strains by phages phi53 and 80alpha The transductants were characterized in detail in respect to transferred plasmids, antibiotic resistance phenotype and lysogenicity with transducing phages. The phage lysate obtained by UV-induction from a MRSA strain successfully transferred the tetracycline plasmid into recipient strain SA113. The transducing phage of this strain differs from the well characterized transducing phage 80alpha in: (i) integrase type Sa6 (L54a), (ii) structure of portal protein, (iii) restriction endonuclease patterns. Conclusion: Two types of plasmids were successfully transferred by generalized transduction: (i) large penicillinase plasmids (36.7, 30.2 and 28 kb), (ii) small tetracycline plasmids (4.0 and 4.4 kb). The plasmids were transferred from two recent hospital-acquired clinical MRSA strains and from archaic MRSA strain Jevons B by transducing phages phi53 and 80alpha. Furthermore, it has been shown that resistance plasmids could be effectively transduced also by some prophages lysogenizing MRSA strains. It is suggested that the prophages are responsible for dissemination of resistance determinants in staphylococcal populations.
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