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Infection and Immunity, May 1999, p. 2299-2305, Vol. 67, No. 5
Department of Microbiology, New York
University School of Medicine, New York, New York
10016,1 and Inflammation Program,
Departments of Internal Medicine and Microbiology, University of
Iowa College of Medicine, Iowa City, Iowa 522422
Received 3 November 1998/Returned for modification 18 December
1998/Accepted 26 February 1999
Fibrinogen-dependent interactions of Staphylococcus
aureus are believed to contribute to bacterial virulence by
promoting bacterial attachment to fibrinogen-coated surfaces and
inducing the formation of bacterial clumps that are likely
resistant to phagocytosis. Although S. aureus produces
several fibrinogen-binding proteins, the cell wall-associated
protein clumping factor (encoded by clfA) appears to be
most important in bacterial interactions with
immobilized or soluble purified fibrinogen. We have compared bacterial
clumping in several strains of S. aureus, including isogenic ClfA+ and ClfA
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Antibacterial Action of Extracellular Mammalian
Group IIA Phospholipase A2 against Grossly Clumped
Staphylococcus aureus
Newman strains, in
the presence of purified rabbit fibrinogen, human plasma, and
inflammatory fluid and examined the effect of clumping on bacterial
sensitivity to mammalian group IIA phospholipase A2 (PLA2).
This enzyme is the major extracellular bactericidal agent in
inflammatory fluid active against S. aureus. Both
ClfA-dependent and ClfA-independent bacterial clumping was observed,
depending on the source and fibrinogen content of the biological fluid. In each case, clumping only partially reduced the antibacterial activity of PLA2, suggesting that this extracellular enzyme can substantially penetrate dense bacterial clumps. Bacterial clumps could
be dispersed by added proteases, restoring full antibacterial activity to PLA2. Thus, the extracellular mobilization of group IIA
PLA2 during inflammation may provide a mechanism by which the host can control the proliferation and survival of S. aureus even after bacterial clumping.
*
Corresponding author. Mailing address: Departments of
Internal Medicine and Microbiology, University of Iowa College of
Medicine, 200 Hawkins Dr., Iowa City, IA 52242. Phone: (319) 384-8622. Fax: (319) 356-4600. E-mail: jerrold-weiss{at}uiowa.edu.
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