The use of cationic surfactants and ionic liquids in the detection of microbial contamination by capillary electrophoresis

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.

Modern Approach to Medical Diagnostics - the Use of Separation Techniques in Microorganisms Detection

Background:

Analytical chemistry and biotechnology as an interdisciplinary fields of science have been developed during many years and are experiencing significant growth, to cover a wide range of microorganisms separation techniques and methods, utilized for medical therapeutic and diagnostic purposes. Currently scientific reports contribute by introducing electrophoretical and immunological methods and formation of devices applied in food protection (avoiding epidemiological diseases) and healthcare (safety ensuring in hospitals).

Methods:

Electrophoretic as well as nucleic-acid-based or specific immunological methods have contributed tremendously to the advance of analyses in recent three decades, particularly in relation to bacteria, viruses and fungi identifications, especially in medical in vitro diagnostics, as well as in environmental or food protection.

Results:

The paper presents the pathogen detection competitiveness of these methods against conventional ones, which are still too time consuming and also labor intensive. The review is presented in several parts following the current trends in improved pathogens separation and detection methods and their subsequent use in medical diagnosis.

Discussion:

Part one, consists of elemental knowledge about microorganisms as an introduction to their characterization: descriptions of divisions, sizes, membranes (cells) components. Second section includes the development, new technological and practical solution descriptions used in electrophoretical procedures during microbes analyses, with special attention paid to bio-samples analyses like blood, urine, lymph or wastewater. Third part covers biomolecular areas that have created a basis needed to identify the progress, limitations and challenges of nucleic-acid-based and immunological techniques discussed to emphasize the advantages of new separative techniques in selective fractionating of microorganisms.

Capillary Zone Electrophoresis with Fraction Collection for Separation, Culturing, and Identification of Bacteria from an Environmental Microbiome

Capillary zone electrophoresis (CZE) can produce high-resolution separations of biological samples, including microbial mixtures. The study of complex populations of microorganisms using CZE is limited because most detectors have limited sensitivity, are destructive, and provide limited information for microbial identification. To address these issues, we developed an integrated capillary zone electrophoresis apparatus to fractionate bacteria from complex mixtures. We deposited fractions onto nutrient agar in a Petri dish for microbial culturing, and we subjected the observed colonies to Sanger sequencing of a phylogenetic marker, the 16S rRNA gene, for microbial identification. We separated and cultured both a single bacteria species, the model Gram-negative organism Escherichia coli, and a complex environmental isolate of primary sewage effluent. Sequence analysis of the 16S rRNA genes from this mixture identified 15 ± 5 distinct bacterial species per run. This approach requires minimal manipulation of microbial populations and combines electrophoretic fractionation of bacterial cells with automated collection for accurate identification of species. This approach should be applicable to microorganisms in general and may enable discrimination of physiologically different cells in complex assemblages, such as in microbiome samples.

Capillary electrophoresis for fast detection of heterogeneous population in colistin-resistant Gram-negative bacteria

It has been shown that diverse strains of bacteria can be separated according to their characteristic surface properties by means of CE. We employed here this analytical technique to the study of colistin-resistance in Gram-negative bacteria, which involves the selection of mutants with modified outer membrane composition resulting in changes of surface cell properties. In the same way as with molecular entities, we performed firstly the validation of an ITP-based CE method for three common pathogenic Gram-negative bacteria namely Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Secondly, we compared the electrophoretic profiles of bacterial samples from a colistin-susceptible clinical isolate of K. pneumoniae and from the corresponding colistin-resistant derivative. By a simple CE run taking a few minutes, the coexistence of several bacterial subpopulations in the colistin-resistant derivative was clearly evidenced. This work encourages further research that would allow applications of CE in clinical laboratory for a daily monitoring of bacterial population in cared patients when "last-chance" colistin treatment is initiated against multidrug-resistant bacteria.

Separation and determination of ephedra alkaloids in traditional Chinese medicine and human urines by capillary electrophoresis coupled with electrochemiluminescence detection

A new approach for the simultaneous determination of ephedrine, methylephedrine, and pseudoephedrine is developed, using capillary electrophoresis coupled with electrochemiluminescence detection with internal standard method. Separation efficiency and sensitivity were improved by use of an ionic liquid. Parameters affecting separation and detection were investigated in detail. Under optimum conditions, the three ephedra alkaloids were well separated and detected. The limits of detection (S/N = 3) of ephedrine, methylephedrine and pseudoephedrine are 4.0 × 10−8, 6.5 × 10−8, and 4.6 × 10−8 mol/L, respectively. The limits of quantitation (S/N = 10) in human urine are 5.3 × 10−7 mol/L for ephedrine, 9.1 × 10−7 mol/L for methylephedrine, and 6.9 × 10−7 mol/L for pseudoephedrine, respectively. The precision (RSD%) of the peak area and the migration time were from 2.2% to 2.5% and from 0.1% to 0.2% within a day and from 2.7% to 3.9% and from 0.4% to 0.8% in three days. The proposed method was successfully applied to the determination of three analytes in traditional Chinese medicine and human urine, and the monitoring of pharmacokinetics of pseudoephedrine in human body.

Collection, storage, and electrophoretic analysis of nanoliter microdialysis samples collected from awake animals in vivo

Microdialysis sampling is an important tool for chemical monitoring in living systems. Temporal resolution is an important figure of merit that is determined by sampling frequency, assay sensitivity, and dispersion of chemical zones during transport from sampling device to fraction collector or analytical system. Temporal resolution has recently been improved by segmenting flow into plugs, so that nanoliter fractions are collected at intervals of 0.1-2 s, thus eliminating temporal distortion associated with dispersion in continuous flow. Such systems, however, have yet to be used with behaving subjects. Furthermore, long-term storage of nanoliter samples created by segmented flow has not been reported. In this work, we have addressed these challenges. A microdialysis probe was integrated to a plug generator that could be stably mounted onto behaving animals. Long-term storage of dialysate plugs was achieved by collecting plugs into high-purity perfluoroalkoxy tubes, placing the tube into hexane and then freezing at -80°C. Slow warming with even temperatures prevented plug coalescence during sample thawing. As a demonstration of the system, plugs were collected from the striatum of behaving rats using a 0.5-mm-long microdialysis probe. Resulting plugs were analyzed 1-4 days later by chip-based electrophoresis. To improve throughput of plug analysis over previous work, the speed of electrophoretic separation was increased by using forced air cooling and 1-butyl-2,3-dimethylimidazolium tetrafluoroborate as a separation buffer additive, allowing resolution of six neuroactive amino acids in 30 s. Concentration changes induced by K(+) microinjections were monitored with 10 s temporal resolution. The improvements reported in this work make it possible to apply segmented flow microdialysis to the study of behaving animals and enable experiments where the analytical system cannot be placed close to the animal.

Use of Ionic Liquid–Based Extraction for Recovery of Salmonella Typhimurium and Listeria monocytogenes from Food Matrices

Methods for rapid separation (<5 h) and concentration of bacteria based on solubilization of complex food matrices have been developed recently to facilitate rapid molecular detection methods. However, a major disadvantage of these protocols is the resulting lack of viability of the microorganisms under study due to extensive use of chemicals and enzymes, which can inhibit subsequent quantitative microbiological analyses. In this study, a new class of organic salts, ionic liquids, were used for solubilization of various foodstuffs, with subsequent molecular and microbiological quantification methods. This approach was applied to gram-positive Listeria monocytogenes and gram-negative Salmonella enterica serovar Typhimurium. By introducing the ionic liquid 1-ethyl-3-methylimidazolium thiocyanate into an existing food solubilization protocol, both molecular and microbiological quantification methods could be used subsequently without losing performance or prolonging the analysis. These experiments resulted in an average recovery of 87% of inoculated bacterial cells with real-time PCR, 85% recovery on nonselective agar plates, and 43% on selective medium. These results illustrate the feasibility of applying ionic liquids in sample pretreatment steps for rapid detection and quantification of bacterial pathogens.

Sterility testing by CE: a comparison of online preconcentration approaches in capillaries with greater internal diameters

Detection of microbial contamination is of critical importance in the medical and the food industry. Rapid tests for the absence or presence of viable microorganisms are in urgent demand. CE is a modern analytical technique that can be adapted for rapid screening of microbial contamination. However, the small dimensions of capillaries allow the introduction of only a small fraction of the sample, which can be problematic when examining large samples. In this article, we examine the possibilities of introducing larger sample volumes using capillaries with greater id together with different stacking techniques. The use of 0.32 mm id capillary and the injection of 60% of the capillary volume led to approximately 120-fold improvement of the injected sample volume over the classical injection 5% of a 0.10-mm id capillary. The setup we described opens new possibilities in sterility testing using CE.

Use of a novel ionic liquid matrix for MALDI-MS analysis of glycopeptides and glycans out of total tryptic digests

In this study, we investigated a novel ionic liquid matrix (ILM), namely, the 1,1,3,3-tetramethylguanidinium salt of 2,4,6-trihydroxyacetophenone (THAP). This matrix[1,1,3,3-tetramethylguanidinium 2,4,6-trihydroxyacetophenone (GTHAP)] turned out to be well suited for the matrix-assisted laser desorption/ionization mass spectrometric analysis of glycopeptides and glycans, and overcame the well-known ionization suppression of carbohydrate structures in the presence of peptides. The matrix was evaluated by two different series of experiments, in each case in comparison with the crystalline THAP matrix. In the first set of experiments, mass spectra were taken from unseparated tryptic digests of three glycoproteins taken as model compounds. Even glycopeptides containing short peptide backbones and large carbohydrate moieties gave high signal intensities when using the ILM though they did not appear in the THAP spectra. In the second set of experiments, the total tryptic digests were treated with endoglycosidase PNGase F to cleave off the N-linked glycans. When using the GTHAP matrix, it was possible to detect the glycans with high intensities in the presence of the tryptic peptides, whereas glycan ionization was completely suppressed when measured with the solid matrix THAP. The extent of metastable decay of glycopeptides was reduced when using the ILM. Altogether, GTHAP proved as a useful ILM particularly being superior to solid matrices in the context of glycosylation analysis.