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Infect. Immun., Apr 1996, 1379-1384, Vol 64, No. 4
MR Yeaman, SS Soldan, MA Ghannoum, JE Edwards Jr, SG Filler and AS Bayer
Thrombin-induced platelet microbicidal protein (tPMP) exerts potent in
vitro microbicidal activity against pathogens commonly found in the
bloodstream, including Staphylococcus aureus, Staphylococcus epidermidis,
and Candida albicans. Localized platelet release of tPMP may be important
in defense against infections involving the vascular endothelium caused by
tPMP-susceptible organisms. In contrast, pathogens capable of surviving in
the presence of tPMP could then exploit the platelet as an adhesive surface
for attachment to damaged endothelium. To examine these hypotheses, we
derived a tPMP-resistant (tPMP(r)) C. albicans strain from its
tPMP-sensitive (tPMP(s)) parental strains were equivalent in vitro as
assessed by genotyping (electrophoretic karyotype and restriction
endonuclease analysis of genomic DNA), biotyping, germination, platelet
aggregation, adherence to vascular endothelial cells, and growth
characteristics. In addition, the tPMP(r) phenotype was stable following
multiple in vitro and in vivo passages. We then investigated the in vivo
relevance of tPMP susceptibility on endovascular infection using a rabbit
model of endocarditis and hematogenous dissemination. Rabbits with
transaortic catheters (n = 15 in each group) were challenged with either
the tPMP(s) or tPMP(r) C. albicans strain. All rabbits developed C.
albicans-induced endocarditis, as determined by the presence of infected
vegetations. In rabbits challenged with tPMP(s) strain (P < 0.001).
These results were seen in the absence of differences in either initial
adherence of strains to cardiac valves or vegetation weights. Furthermore,
although these C. albicans strains induced equivalent rates and extent of
hematogenous renal infection, only the tPMP(r) strain disseminated
hematogenously to the spleen (15 of 15 rabbits) versus 0 of 15 [tpmp(s)
strain]; P < 0.0001). Thus, tPMP(r) C. albicans caused more-severe
endocarditis and produced greater metastatic sequelae than the tPMP(s)
counterpart.
Copyright © 1996, American Society for Microbiology
Resistance to platelet microbicidal protein results in increased severity of experimental Candida albicans endocarditis
Division of Infectious Diseases, St. John's Cardiovascular Research Center, Los Angeles County Harbor-UCLA Medical Center, Torrance, California 90509, USA.
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