title: Biophysical separation of Staphylococcus epidermidis strains based on antibiotic resistance.
abstract: 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.
authors.affiliation: Arizona State University, Department of Chemistry and Biochemistry, Tempe, AZ 85287, USA. mhayes@asu.edu.
authors.forename: Paul V
authors.initials: PV
authors.lastname: Jones
authors.forename: Shannon
authors.initials: S
authors.lastname: Huey
authors.forename: Paige
authors.initials: P
authors.lastname: Davis
authors.forename: Ryan
authors.initials: R
authors.lastname: Yanashima
authors.forename: Ryan
authors.initials: R
authors.lastname: McLemore
authors.forename: Alex
authors.initials: A
authors.lastname: McLaren
authors.forename: Mark A
authors.initials: MA
authors.lastname: Hayes
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002469:Cell Separation / Q000295:instrumentation; D004352:Drug Resistance, Microbial; D004553:Electric Conductivity; D004586:Electrophoresis / Q000295:instrumentation; D005839:Gentamicins / Q000494:pharmacology; D006801:Humans; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology*; D013212:Staphylococcus epidermidis / Q000187:drug effects / Q000302:isolation & purification*
chemical_list: D000900:Anti-Bacterial Agents; D005839:Gentamicins