Biophysical separation of Staphylococcus epidermidis strains based on antibiotic resistance

• Published in: Analyst (London) Vol. 14; no. 15; pp. 5152 - 5161
• Main Authors: Jones, Paul V, Huey, Shannon, Davis, Paige, McLemore, Ryan, McLaren, Alex, Hayes, Mark A
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 07.08.2015
• Subjects: Anti-Bacterial Agents - pharmacology; Cell Separation - instrumentation; Chemistry; Drug Resistance, Microbial; Electric Conductivity; Electrophoresis - instrumentation; Gentamicins - pharmacology; Humans; Staphylococcal Infections - drug therapy; Staphylococcal Infections - microbiology; Staphylococcus epidermidis - drug effects; Staphylococcus epidermidis - isolation & purification
• ISSN: 0003-2654; 1364-5528
• DOI: 10.1039/c5an00906e

Electrophoretic and dielectrophoretic approaches to separations can provide unique capabilities. In the past, capillary and microchip-based approaches to electrophoresis have demonstrated extremely high-resolution separations. More recently, dielectrophoretic systems have shown excellent results for the separation of bioparticles. Here we demonstrate resolution of a difficult pair of targets: gentamicin resistant and susceptible strains of Staphylococcus epidermidis . This separation has significant potential implications for healthcare. This establishes a foundation for biophysical separations as a direct diagnostic tool, potentially improving nearly every figure of merit for diagnostics and antibiotic stewardship. The separations are performed on a modified gradient insulator-based dielectrophoresis (g-iDEP) system and demonstrate that the presence of antibiotic resistance enzymes (or secondary effects) produces a sufficient degree of electrophysical difference to allow separation. The differentiating factor is the ratio of electrophoretic to dielectrophoretic mobilities. This factor is 4.6 ± 0.6 × 10 9 V m −2 for the resistant strain, versus 9.2 ± 0.4 × 10 9 V m −2 for the susceptible strain. Using g-iDEP separation, this difference produces clear and easily discerned differentiation of the two strains. Gradient insulator-based dielectrophoresis used to generate separation and concentration of Staphylococcus epidermidis , gentamicin-resistant and susceptible strains.