Rapid Analysis for Staphylococcus aureus via Microchip Capillary Electrophoresis

Abstract

Staphylococcus aureus (S. aureus) is one of the most common pathogens for nosocomial and community infections, which is closely related to the occurrence of pyogenic and toxic diseases in human beings. In the current study, a lab-built microchip capillary electrophoresis (microchip CE) system was employed for the rapid determination of S. aureus, while a simple-to-use space domain internal standard (SDIS) method was carried out for the reliable quantitative analysis. The precision, accuracy, and reliability of SDIS were investigated in detail. Noted that these properties could be elevated in SDIS compared with traditional IS method. Remarkably, the PCR products of S. aureusnuc gene could be identified and quantitated within 80 s. The theoretical detection limit could achieve a value of 0.066 ng/μL, determined by the using SDIS method. The current work may provide a promising detection strategy for the high-speed and highly efficient analysis of pathogens in the fields of food safety and clinical diagnosis.

Keywords: Staphylococcus aureus; microchip capillary electrophoresis; nuc gene; space domain internal standard method.

Figure 1

Sketch of the lab-built microchip capillary electrophoresis (CE) system.

Figure 2

Electrophoretograms of the standard 100 bp ladder marker ranging between 100~600 bp: (a) run-to-run tests performed in 1% hydroxyethylcellulose (HEC) (1300 K) at 800 V; (b) fluorescence signal (FS) and time-domain-detected signal (DS) ratios of run-to-run tests; (c) HEC (1300 K) matrix concentration ranging 0.4–1%; (d) FS and DS ratios of matrix concentrations ranging 0.4–1%; (e) separation voltages ranging 600–1200 V; (f) FS and DS ratios of separation voltages ranging 600–1200 V. The dash lines in (d) and (f) were the auxiliary lines for observation.

Figure 3

(a) Identification for the PCR products of nuc gene; (b) the plot of DNA size versus migration time (the red star represents the PCR product of S. aureus). The electrophoresis was performed in 1% HEC (1300 K) at 800 V.

Figure 4

(a) Electrophoretograms for PCR products of nuc gene in different concentrations; (b) the relationship between the detected concentration and the diluted concentration of the PCR products. The electrophoretic conditions were the same as that of in Figure 3.