BACKGROUND: The extent to which the horizontal transfer of virulence genes has contributed to the emergence of contemporary virulent strains of methicillin-resistant Staphylococcus aureus (MRSA) in hospital and community settings is poorly understood. METHODS: Epidemiologically well-characterized MRSA isolates collected over 8.5 years were genotyped and tested for the presence of 34 virulence genes. RESULTS: Six strain types accounted for 88.2% of all MRSA infections. The evolution of contemporary hospital and community phenotypes within the CC8 and CC30 lineages--2 background genomes that produced historical pandemic MRSA clones--were associated with multiple horizontal acquisitions of virulence genes. The epidemic community phenotype of a CC8 strain, designated ST8:USA300, was linked to the acquisition of staphylococcal cassette chromosome (SCC)mec type IV, the genes for Panton-Valentine leukocidin (PVL), and the enterotoxin Q and K genes. Similarly, the epidemic community phenotype of a CC30 strain, ST30:USA1100, was linked to the acquisition of SCCmec type IV and the pvl genes. In contrast, the epidemic hospital phenotype of another CC30 strain, ST36:USA200, was associated with the acquisition of SCCmec type II, the enterotoxin A gene, and the toxic shock syndrome toxin 1 gene. The pvl genes appear not to be essential for the evolution OF other community-associated strains of mrsa, including ST8:USA500 and ST59:USA1000. CONCLUSIONS: The horizontal transfer of virulence genes, although infrequent, is epidemiologically associated with the emergence of new virulent strains of MRSA.
BACKGROUND: The extent to which the horizontal transfer of virulence genes has contributed to the emergence of contemporary virulent strains of methicillin-resistant Staphylococcus aureus (MRSA) in hospital and community settings is poorly understood. METHODS: Epidemiologically well-characterized MRSA isolates collected over 8.5 years were genotyped and tested for the presence of 34 virulence genes. RESULTS: Six strain types accounted for 88.2% of all MRSA infections. The evolution of contemporary hospital and community phenotypes within the CC8 and CC30 lineages--2 background genomes that produced historical pandemic MRSA clones--were associated with multiple horizontal acquisitions of virulence genes. The epidemic community phenotype of a CC8 strain, designated ST8:USA300, was linked to the acquisition of staphylococcal cassette chromosome (SCC)mec type IV, the genes for Panton-Valentine leukocidin (PVL), and the enterotoxin Q and K genes. Similarly, the epidemic community phenotype of a CC30 strain, ST30:USA1100, was linked to the acquisition of SCCmec type IV and the pvl genes. In contrast, the epidemic hospital phenotype of another CC30 strain, ST36:USA200, was associated with the acquisition of SCCmec type II, the enterotoxin A gene, and the toxic shock syndrome toxin 1 gene. The pvl genes appear not to be essential for the evolution OF other community-associated strains of mrsa, including ST8:USA500 and ST59:USA1000. CONCLUSIONS: The horizontal transfer of virulence genes, although infrequent, is epidemiologically associated with the emergence of new virulent strains of MRSA.
Authors: Francis Alonzo; Meredith A Benson; John Chen; Richard P Novick; Bo Shopsin; Victor J Torres Journal: Mol Microbiol Date: 2011-12-20 Impact factor: 3.501
Authors: Kati Seidl; Arnold S Bayer; Vance G Fowler; James A McKinnell; Wessam Abdel Hady; George Sakoulas; Michael R Yeaman; Yan Q Xiong Journal: Antimicrob Agents Chemother Date: 2010-11-22 Impact factor: 5.191
Authors: Cleo E Rolle; Juan Chen; Irena Pastar; Tatiana C P Cardenas; Roberto Perez; Suzanne Hower; Franco Ferracci; Richard Snyder; Marjana Tomic-Canic; Lisa R W Plano Journal: Immunol Res Date: 2013-12 Impact factor: 2.829