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Antimicrobial Agents and Chemotherapy, March 1998, p. 564-570, Vol. 42, No. 3
Division of Infectious Diseases,
Received 10 June 1997/Returned for modification 20 September
1997/Accepted 7 January 1998
Some methicillin-resistant strains of Staphylococcus
aureus are defective in the production of major surface
components such as protein A, clumping factor, or other important
adhesins to extracellular matrix components which may play a role in
bacterial colonization and infection. To evaluate the impact of
methicillin resistance (mec) determinants on bacterial
adhesion mediated by fibrinogen or fibronectin adhesins, we compared
the in vitro attachment of two genetically distinct susceptible strains
(NCTC8325 and Newman) to protein-coated surfaces with that of isogenic
methicillin-resistant derivatives. All strains containing an intact
mec element in their chromosomes were found to be defective
in adhesion to fibrinogen and fibronectin immobilized on
polymethylmethacrylate coverslips, regardless of the presence or
absence of additional mutations in the femA,
femB, or femC gene, known to decrease
expression of methicillin resistance in S. aureus. Western
ligand affinity blotting or immunoblotting of cell wall-associated
adhesins revealed similar contents of fibrinogen- or
fibronectin-binding proteins in methicillin-resistant strains compared
to those of their methicillin-susceptible counterparts. In contrast to
methicillin-resistant strains carrying a mec element in
their genomes, methicillin-resistant strains constructed in vitro, by
introducing the mecA gene on a plasmid, retained their
adhesion phenotypes. In conclusion, the chromosomal insertion of the
mec element into genetically defined strains of S. aureus impairs the in vitro functional activities of fibrinogen or fibronectin adhesins without altering their production. This effect
is unrelated to the activity of the mecA gene.
0066-4804/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Introduction of the mec Element
(Methicillin Resistance) into Staphylococcus aureus Alters
In Vitro Functional Activities of Fibrinogen and Fibronectin
Adhesins

*
Corresponding author. Mailing address: Division of
Infectious Diseases, University Hospital, CH 1211 Geneva 14, Switzerland. Phone: (4122) 37 29 826. Fax: (4122) 37 29 830. E-mail:
vaudaux{at}dminov1.hcuge.ch.
Present address: Laboratorio di Batteriologica, Istituto di Clinica
di Malattie Infettive, Pavia, Italy.
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