Capillary electrophoresis in a fused-silica capillary with surface roughness gradient

Bacteriophage replication on permissive host cells in fused silica capillary with nanostructured part as potential of electrophoretic methods for developing phage applications

Phage therapy could offer a safe and effective alternative to antibiotic treatment of infections caused by Gram-positive bacterium Staphylococcus aureus that have emerged as a significant threat in hospital and community environment and is attracting growing interest among clinicians. The legislation process of approving the phage therapeutics by pharmaceutical authorities requires rapid analytical techniques for assessment of phage activity. Here, we present a three-step method for on-line monitoring the phage effect on bacterial cells dynamically adhered from microliter volumes of high conductivity matrix onto the inner surface of fused silica capillary with a part etched with supercritical water. Phage K1/420 particles of the Kayvirus genus generated by propagation on the host S. aureus cells together with the uninfected cells were concentrated, separated and detected using capillary electrophoretic methods. The phage interactions with selected S. aureus strains exhibiting differences in phage susceptibility were compared. The method allowed determination of the phage burst size and time of phage latent period in analyzed strains. Apart from enumeration of bacteriophages by the plaque assays, the proposed method is suitable for phage activity testing.

Rapid Isolation, Propagation, and Online Analysis of a Small Number of Therapeutic Staphylococcal Bacteriophages from a Complex Matrix

A method for the fast isolation, propagation, and characterization of very low count bacteriophages active against pathogenic bacterial strains is described in this study. Bacteriophages with a count of 10² phage particles were dynamically adhered from the maximum 10 mL blood plasma sample onto the nanostructured part of the fused silica capillary. One-step propagation of phage particles of genus Kayvirus inside the etched capillary on 10⁴ Staphylococcus aureus host cells increased their number to 6 × 10⁴ phage particles. Phage particles were concentrated online and separated by capillary electrophoretic methods. No phage replication occurred when the phage-resistant S. aureus or Escherichia coli cells were used. Two-step phage propagation in the capillary allowed an increase in the total virion count to up to 6 × 10⁵ phage particles and subsequent off-line matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis of the phage zone collected after capillary electrophoresis. Relative standard deviations of the phage peak area were at most 2.3%. We expect that the method of isolating bacteriophages from blood plasma and their simultaneous identification will facilitate clinical studies of phage preparations and contribute to pharmacokinetics studies during phage therapy. This approach is also suitable for capturing and enriching new phages from the environment when a susceptible indicator strain is available.

Identification of Aspergillus Conidia in Bronchoalveolar Lavage Using Offline Combination of Capillary Electrophoresis in Supercritical Water-Treated Fused Silica Capillary and Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

Diagnosis of fungal infection in lung parenchyma is relatively difficult. Bronchoscopy with bronchoalveolar lavage is very useful in its diagnosing. Therefore, a method for rapid online concentration and analysis of Aspergillus conidia in bronchoalveolar lavage fluid using the combination of transient isotachophoresis (tITP) and micellar electrokinetic chromatography (MEKC) with subsequent off-line identification of the separated conidia by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is described in this study. In the proposed procedure, conidia were first dynamically adhered onto the roughened part of the inner surface of a fused silica capillary prepared by etching with supercritical water. Then the adhered conidia were desorbed, concentrated, and separated using a combination of tITP and MEKC. Finally, the fractions containing the separated conidia were collected from the capillary and analyzed by MALDI-TOF MS. The adhesion efficiency under the optimized experimental conditions was about 80%. This rapid diagnosis will contribute to timely initiation of therapy and increase the patient's chances of survival.

Online Concentration of Bacteria from Tens of Microliter Sample Volumes in Roughened Fused Silica Capillary with Subsequent Analysis by Capillary Electrophoresis and Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

This study presents a timely, reliable, and sensitive method for identification of pathogenic bacteria in clinical samples based on a combination of capillary electrophoresis with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. In this respect, a part of a single-piece fused silica capillary was etched with supercritical water with the aim of using it for static or dynamic cell-surface adhesion from tens of microliter sample volumes. The conditions for this procedure were optimized. Adhered cells of Staphylococcus aureus (methicillin-susceptible or methicillin-resistant) and of Pseudomonas aeruginosa were desorbed and preconcentrated from the rough part of the capillary surface using transient isotachophoretic stacking from a high conductivity model matrix. The charged cells were swep and separated again in micellar electrokinetic chromatography using a nonionogenic surfactant. Static adhesion of the cells onto the roughened part of the capillary is certainly volumetric limited. Dynamic adhesion allows the concentration of bacteria from 100 μL volumes of physiological saline solution, bovine serum, or human blood with the limits of detection at 1.8 × 10², 1.7 × 10³, and 1.0 × 10³ cells mL^-1, respectively. The limits of detection were the same for all three examined bacterial strains. The recovery of the method was about 83% and it was independent of the sample matrix. A combination of capillary electrophoresis with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry required at least 4 × 10³ cells mL^-1 to obtain reliable results. The calibration plots were linear (R² = 0.99) and the relative standard deviations of the peak area were at most 2.2%. The adhered bacteria, either individual or in a mixture, were online analyzed by micellar electrokinetic chromatography and then collected from the capillary and off-line analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry without interfering matrix components.