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In vitro resistance to thrombin-induced platelet microbicidal protein in isolates of Staphylococcus aureus from
V G Fowler1, L M McIntyre, M R Yeaman
1Division of Infectious Diseases, Duke University Medical Center, Durham, NC 27710, USA. fowle003@mc.duke.edu
Abstract:
Platelet microbicidal proteins (PMPs) are small antimicrobial peptides secreted by mammalian platelets. In vitro resistance of Staphylococcus aureus strains to PMPs correlates with more extensive disease in experimental infective endocarditis (IE). To determine whether this same relationship exists in human S. aureus IE, we evaluated the in vitro PMP susceptibility phenotype of isolates from 58 prospectively-identified patients with definite S. aureus IE. On multivariate analyses, patients with S. aureus IE complicating an infected intravascular device were significantly more likely to have IE caused by a PMP-resistant strain (P=.0193). No correlations were detected between in vitro PMP resistance among S. aureus strains and the severity of human IE. This work supports the concept that in vitro PMP resistance in clinical S. aureus strains is associated with important clinical characteristics of S. aureus endovascular infections in vivo.
Insights
Platelet microbicidal proteins (PMPs) combat Staphylococcus aureus infections. PMP resistance in S. aureus strains is linked to intravascular device infections, but not disease severity in human infective endocarditis.
Area of Science:
- Microbiology
- Immunology
- Infectious Diseases
Background:
- Platelet microbicidal proteins (PMPs) are antimicrobial peptides produced by platelets.
- In vitro PMP resistance in Staphylococcus aureus is linked to disease severity in experimental models.
- The relationship between PMP resistance and human infective endocarditis (IE) severity is not well understood.
Purpose of the Study:
- To investigate the association between in vitro PMP resistance of Staphylococcus aureus and clinical characteristics in human IE.
- To determine if PMP resistance correlates with disease severity in patients with S. aureus IE.
Main Methods:
- Prospective evaluation of in vitro PMP susceptibility of S. aureus isolates from 58 patients with definite IE.
- Multivariate analyses were used to assess correlations between PMP resistance and clinical factors.
Main Results:
- PMP resistance in S. aureus isolates was significantly associated with IE complicating an infected intravascular device (P=.0193).
- No correlation was found between in vitro PMP resistance and the severity of human S. aureus IE.
- PMP resistance is associated with specific clinical features of S. aureus endovascular infections.
Conclusions:
- In vitro PMP resistance in clinical S. aureus strains is linked to specific clinical characteristics, such as intravascular device infections.
- PMP resistance does not appear to correlate with the severity of human infective endocarditis.
- This study highlights the clinical relevance of PMP resistance in S. aureus endovascular infections.