Virulent combinations of adhesin and toxin genes in natural populations of Staphylococcus aureus.
Most cases of severe Staphylococcus aureus disease cannot be explained by the action of a single virulence determinant, and it is likely that a number of factors act in combination during the infective process. This study examined the relationship between disease in humans and a large number of putative virulence determinants, both individually and in combination. S. aureus isolates (n = 334) from healthy blood donors and from patients with invasive disease were compared for variation in the presence of 33 putative virulence determinants. After adjusting for the effect of clonality, seven determinants (fnbA, cna, sdrE, sej, eta, hlg, and ica) were significantly more common in invasive isolates. All seven factors contributed independently to virulence. No single factor predominated as the major predictor of virulence, their effects appearing to be cumulative. No combinations of the seven genes were either more or less likely to cause disease than others with the same number of virulence-associated genes. There was evidence of considerable horizontal transfer of genes on a background of clonality. Our findings also suggested that allelic variants of a polymorphic locus can make different contributions to the disease process, further study of which is likely to expand our understanding of staphylococcal disease pathogenesis.
Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, University of Oxford, United Kingdom. sharon.peacock@ndcls.ox.ac.uk
Sharon J
SJ
Peacock
Catrin E
CE
Moore
Anita
A
Justice
Maria
M
Kantzanou
Lisa
L
Story
Kathryn
K
Mackie
Gael
G
O'Neill
Nicholas P J
NP
Day
D018829:Adhesins, Bacterial / Q000235:genetics*; D000483:Alleles; D001427:Bacterial Toxins / Q000235:genetics*; D001483:Base Sequence; D017714:Community-Acquired Infections / Q000209:etiology / Q000382:microbiology; D003428:Cross Infection / Q000209:etiology / Q000382:microbiology; D004269:DNA, Bacterial / Q000235:genetics; D022761:Gene Transfer, Horizontal; D005798:Genes, Bacterial; D014644:Genetic Variation; D005828:Genetics, Population; D005838:Genotype; D006801:Humans; D015810:Linkage Disequilibrium; D015999:Multivariate Analysis; D010641:Phenotype; D013203:Staphylococcal Infections / Q000209:etiology / Q000382:microbiology; D013211:Staphylococcus aureus / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity*; D014774:Virulence / Q000235:genetics
D018829:Adhesins, Bacterial; D001427:Bacterial Toxins; D004269:DNA, Bacterial