Genetic variation among hospital isolates of methicillin-sensitive Staphylococcus aureus: Evidence for horizontal transfer of virulence genes

Citation
Pcl. Moore et Ja. Lindsay, Genetic variation among hospital isolates of methicillin-sensitive Staphylococcus aureus: Evidence for horizontal transfer of virulence genes, J CLIN MICR, 39(8), 2001, pp. 2760-2767
Citations number
59
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Clinical Immunolgy & Infectious Disease",Microbiology
Journal title
JOURNAL OF CLINICAL MICROBIOLOGY
ISSN journal
0095-1137 → ACNP
Volume
39
Issue
8
Year of publication
2001
Pages
2760 - 2767
Database
ISI
SICI code
0095-1137(200108)39:8<2760:GVAHIO>2.0.ZU;2-D
Abstract
Staphylococcus aureus strains often carry in their genomes virulence genes that are not found in all strains and that may be carried on discrete genet ic elements. Strains also differ in that they carry one of four classes of an accessory gene regulator (agr) locus, an operon that regulates virulence factor expression and that has been proposed to be a therapeutic target. T o look at their distribution among hospital strains, we investigated 38 met hicillin-sensitive S. aureus isolates, classifying the isolates by agr clas s and screening them for the presence and restriction fragment length polym orphisms (RFLPs) of 12 core and 14 accessory virulence genes. Twenty-three (61%) were agr class I, 10 (26%) were agr class II, and 5 (13%) were agr cl ass III. None were agr class IV. The S. aureus strains had distinguishable RFLP profiles, although clusters of isolates with clearly related core gene profiles were found among our strains, including all five agr class III st rains, two sets of six strains within agr class I, and six strains within a gr class II. Within these clusters there was evidence of horizontal acquisi tion and/or loss of multiple accessory virulence genes. Furthermore, two is olates from the same patient were identical except for the presence of the sea gene, indicating that movement of mobile elements may occur in vivo. Se veral strong correlations with the carriage of virulence genes between stra ins were seen, including a positive correlation between tst and agr class I II and negative correlations between tst and lukE-splB and between lukE-spl B and seg-sei. This suggests that the core genome or the presence of access ory genetic elements within a strain may influence acquisition and loss of other elements encoding virulence genes.