Affiliation:
1. Faculté de Médecine Laennec, Centre National de Référence des Toxémies à Staphylocoques, 69372 Lyon Cedex 08
2. UMR CNRS 5557, Ecologie Microbienne, Université Claude Bernard-Lyon 1, UMR CNRS 5557, and INRA, 69622 Villeurbanne
3. UMR CNRS 5558, Laboratoire de Biométrie et Biologie Evolutive, Université Claude Bernard-Lyon 1, 69622 Villeurbanne Cedex, France
Abstract
ABSTRACT
The expression of most
Staphylococcus aureus
virulence factors is controlled by the
agr
locus, which encodes a two-component signaling pathway whose activating ligand is an
agr
-encoded autoinducing peptide (AIP). A polymorphism in the amino acid sequence of the AIP and of its corresponding receptor divides
S. aureus
strains into four major groups. Within a given group, each strain produces a peptide that can activate the
agr
response in the other member strains, whereas the AIPs belonging to different groups are usually mutually inhibitory. We investigated a possible relationship between
agr
groups and human
S. aureus
disease by studying 198
S. aureus
strains isolated from 14 asymptomatic carriers, 66 patients with suppurative infection, and 114 patients with acute toxemia. The
agr
group and the distribution of 24 toxin genes were analyzed by PCR, and the genetic background was determined by means of amplified fragment length polymorphism (AFLP) analysis. The isolates were relatively evenly distributed among the four
agr
groups, with 61 strains belonging to
agr
group I, 49 belonging to group II, 43 belonging to group III, and 45 belonging to group IV. Principal coordinate analysis performed on the AFLP distance matrix divided the 198 strains into three main phylogenetic groups, AF1 corresponding to strains of
agr
group IV, AF2 corresponding to strains of
agr
groups I and II, and AF3 corresponding to strains of
agr
group III. This indicated that the
agr
type was linked to the genetic background. A relationship between genetic background,
agr
group, and disease type was observed for several toxin-mediated diseases: for instance,
agr
group IV strains were associated with generalized exfoliative syndromes, and phylogenetic group AF1 strains with bullous impetigo. Among the suppurative infections, endocarditis strains mainly belonged to phylogenetic group AF2 and
agr
groups I and II. While these results do not show a direct role of the
agr
type in the type of human disease caused by
S. aureus
, the
agr
group may reflect an ancient evolutionary division of
S. aureus
in terms of this species’ fundamental biology.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Reference30 articles.
1. Arbuthnott, J. P., D. C. Coleman, and J. S. de Azavedo. 1990. Staphylococcal toxins in human disease. Soc. Appl. Bacteriol. Symp. Ser.19:101S–107S.
2. Bingen, E., B. Picard, N. Brahimi, S. Mathy, P. Desjardins, J. Elion, and E. Denamur. 1998. Phylogenetic analysis of Escherichia coli strains causing neonatal meningitis suggests horizontal gene transfer from a predominant pool of highly virulent B2 group strains. J. Infect. Dis.177:642–650.
3. Clonal Associations among
Staphylococcus aureus
Isolates from Various Sites of Infection
4. Day, N. P., C. E. Moore, M. C. Enright, A. R. Berendt, J. M. Smith, M. F. Murphy, S. J. Peacock, B. G. Spratt, and E. J. Feil. 2001. A link between virulence and ecological abundance in natural populations of Staphylococcus aureus. Science292:114–116.
5. De Buyser, M. L., A. Morvan, F. Grimont, and N. El Solh. 1989. Characterization of Staphylococcus species by ribosomal RNA gene restriction patterns. J. Gen. Microbiol.135:989–999.