A geographic variant of the Staphylococcus aureus Panton-Valentine leukocidin toxin and the origin of community-associated methicillin-resistant S. aureus USA300.
J Infect Dis
; 197(2): 187-94, 2008 Jan 15.
Article
em En
| MEDLINE
| ID: mdl-18177252
ABSTRACT
BACKGROUND:
The majority of recent community-associated methicillin-resistant Staphylococcus aureus (MRSA) infections in the United States have been caused by a single clone, USA300. USA300 secretes Panton-Valentine leukocidin (PVL) toxin, which is associated with highly virulent infections.METHODS:
We sequenced the PVL genes of 174 S. aureus isolates from a global clinical sample. We combined phylogenetic reconstruction and protein modeling methods to analyze genetic variation in PVL.RESULTS:
Nucleotide variation was detected at 12 of 1726 sites. Two PVL sequence variants, the R variant and the H variant, were identified on the basis of a substitution at nt 527. Of sequences obtained in the United States, 96.7% harbor the R variant, whereas 95.6% of sequences obtained outside the United States harbor the H variant; 91.3% of MRSA isolates harbor the R variant, and 91.3% of methicillin-susceptible strains harbor the H variant. A molecular model of PVL shows 3 mechanisms by which the amino acid substitution may affect PVL function.CONCLUSIONS:
All sampled PVL genes appear to share a recent common ancestor and spread via a combination of clonal expansion and horizontal transfer. US isolates harbor a variant of PVL that is strongly associated with MRSA infections. Protein modeling reveals that this variant may have functional significance. We propose a hypothesis for the origin of USA300.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Staphylococcus aureus
/
Toxinas Bacterianas
/
Variação Genética
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Resistência a Meticilina
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Infecções Comunitárias Adquiridas
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Exotoxinas
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Leucocidinas
Tipo de estudo:
Risk_factors_studies
Limite:
Adult
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Child
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Child, preschool
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Humans
Idioma:
En
Ano de publicação:
2008
Tipo de documento:
Article