Rapid Isolation of Staphylococcus aureus Pathogens from Infected Clinical Samples Using Magnetic Beads Coated with Fc-Mannose Binding Lectin.
Here we describe how Staphylococcus aureus bacteria can be rapidly isolated from clinical samples of articular fluid and synovial tissue using magnetic beads coated with the engineered chimeric human opsonin protein, Fc-mannose-binding lectin (FcMBL). The FcMBL-beads were used to capture and magnetically remove bacteria from purified cultures of 12 S. aureus strains, and from 8 articular fluid samples and 4 synovial tissue samples collected from patients with osteoarthritis or periprosthetic infections previously documented by positive S. aureus cultures. While the capture efficiency was high (85%) with purified S. aureus strains grown in vitro, direct FcMBL-bead capture from the clinical samples was initially disappointing (< 5% efficiency). Further analysis revealed that inhibition of FcMBL binding was due to coating of the bacteria by immunoglobulins and immune cells that masked FcMBL binding sites, and to the high viscosity of these complex biological samples. Importantly, capture of pathogens using the FcMBL-beads was increased to 76% efficiency by pretreating clinical specimens with hypotonic washes, hyaluronidase and a protease cocktail. Using this approach, S. aureus bacteria could be isolated from infected osteoarthritic tissues within 2 hours after sample collection. This FcMBL-enabled magnetic method for rapid capture and concentration of pathogens from clinical samples could be integrated upstream of current processes used in clinical microbiology laboratories to identify pathogens and perform antibiotic sensitivity testing when bacterial culture is not possible or before colonies can be detected.
Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts, United States of America.|Hospital Joseph-Ducuing, Toulouse, France.
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Bicart-See
Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts, United States of America.|Universite de Versailles, St Quentin, France.
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Rottman
Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts, United States of America.
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Cartwright
Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts, United States of America.
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Seiler
Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts, United States of America.
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Gamini
Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts, United States of America.
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Rodas
INSERM 1043, Toulouse, France.
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Penary
Hospital Joseph-Ducuing, Toulouse, France.
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Giordano
INSERM 1043, Toulouse, France.
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Oswald
Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts, United States of America.
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Super
Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts, United States of America.|Harvard Medical School and Boston Children's Hospital, Boston, Massachusetts, United States of America.|Harvard John A. Paulson School of Engineering and Applied Sciences, Cambridge, Massachusetts, United States of America.
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Ingber
D005260:Female; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000737:chemistry*; D060526:Magnetic Fields; D008297:Male; D037601:Mannose-Binding Lectin / Q000737:chemistry*; D008863:Microspheres; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D013211:Staphylococcus aureus / Q000254:growth & development* / Q000302:isolation & purification*
D007141:Immunoglobulin Fc Fragments; D037601:Mannose-Binding Lectin; D011993:Recombinant Fusion Proteins