Clinical application of a rapid microbiological test based on capillary zone electrophoresis to assess local skin infection

Fractionation of bacteria by electrophoresis as pre-separation method before MALDI-MS detection

The present study attempted to apply the capillary electrophoresis technique for the fractionation and separation of S. Staphylococcus hominis and Escherichia coli bacteria isolated from urine samples and the detection of migrated fraction with spectrometric method. This involved the selection of suitable conditions for separation as well as the identification of pathogens. The result of the research was the separation of Gram-negative and Gram-positive bacteria, as well as their subsequent identification by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry using two different approaches (culture of fractions on an agar plate and direct analysis of the collected fractions). The preliminary results provide a solid basis for further research on the use of electromigration techniques with LDI detection to identify pathogens such as bacteria and viruses in biological samples.

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.

The influence of different pH on the electrophoretic behaviour of Saccharomyces cerevisiae modified by calcium ions

The effect of a different pH on Saccharomyces cerevisiae cells modified with calcium ions was investigated by the capillary zone electrophoresis technique. For the identification of the wild strain of S. cerevisiae, the ribosomal nucleic acid sequencing and internal transcribed spacer sequencing as well as spectrometric approach were applied. The potentiometric titration and Fourier transform infrared spectroscopy have shown the occurrence of active functional groups such as carboxyl, amine/hydroxyl, phosphate/hydrogen phosphate groups on the surface of native yeast cells. Moreover, the spectroscopy study in a medium infrared range was carried out to identify the functional groups of yeast cells that participate in calcium ions binding interaction. Furthermore, the microscopic and spectrometric analysis shows that the pH value of the calcium ions solution has a significant effect on the intensity yeast cells clumping. Additionally, the impact of yeast cell clumping on the electrophoretic behaviours was examined. The modification of surface functional groups by calcium ions significantly affected the efficiency of electrophoretic separation. However, these changes did not affect the accuracy of S. cerevisiae identification by MALDI equipment with BioTyper platform. These results form the analytical solution for coupling of electrophoresis and MALDI-TOF MS technique.

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.