Approach For Detection Of Bacteria Research Articles

Analyzing bacterial detection and transport using redox impact electrochemistry

Understanding bacterial transport dynamics, particularly at the single-particle level, is crucial across diverse fields from environmental science to biomedical research. In recent times, the emerging impact electrochemistry method offers a transformative approach for detection of bacteria at the single-particle level. The method employs the principle of single-entity electrochemistry to scrutinize electrochemical processes during interaction with the working electrode. In this study, we utilized redox impact electrochemistry to detect bacteria and analyze their transport processes towards the working electrode. Stochastic detection using redox reactions at the ultramicroelectrode enabled the detection of individual bacteria, with collision resulting in a current spike signal due to charge transfer. Notably, the detection of bacteria was demonstrated at an exceptionally low concentration (100 CFU/mL), with recorded current spikes reaching approximately 8.1 nA. Analysis of integrated areas under these spikes unveiled a diverse distribution of charge transfer at the ultramicroelectrode during redox reactions, implying variations in bacterial sizes, collision positions on the electrode surface, and redox activity among bacteria. Remarkably, the average charge transfer per bacterium between E. coli and the electrode was found to be (244 ± 24) pC, underscoring the intrinsic redox activity of the bacteria, equivalent to (2.52 ± 0.25) × 10−15 mol. Additionally, our investigation explored the effects of cell transport mechanisms, including diffusion, migration, convection, and settlement on stochastic interactions of the bacteria at the ultramicroelectrode. Through the collision frequency calculations, we found that migration is the primary factor shaping bacterial transport, with gravitational cell settlement also exerting a significant influence.

Application of silver nanoparticles and CdSe quantum dots sensitized with of C-like lectin for detection of St. aureus. Comparison of various approaches

C-type lectin from hen egg shell as a recognition ligand for detection of St. aureus was applied. Three approaches for detection of bacteria were used and the sensitivities of the assays were compared. Two of them included spherical and anisotropic silver nanoparticles sensitized by lectin. In these cases the optical changes as a result of interaction of sensitized nanoparticles with bacteria were measured. In the third approach hybrid system of CdSe quantum dots-anisotropic silver nanoparticles sensitized by lectin was applied. Here fluorescent changes as a result of resonance energy transfer between nanoparticles as consequence of their interaction with bacteria were measured. The data demonstrate that assays with spherical silver nanoparticles permit to detect St. aureus in the range of 6 × 104/mL–2 × 107/mL, anisotropic silver nanoparticles in the range of 2 × 105/mL–1 × 108/mL, CdSe-Ag hybrid system in the range of 6 × 103/mL–2 × 107/mL. The data demonstrate that hybrid system CdSe-Ag with resonance energy transfer provides the best sensitivity.

Bacteria detection by flow cytometry

Since bacterial infection of the recipient has become the most frequent infection risk in transfusion medicine, suitable methods for bacteria detection in blood components are of great interest. Platelet concentrates are currently the focus of attention, as they are stored under temperature conditions, which enable the multiplication of most bacteria species contaminating blood donations. Rapid methods for bacteria detection allow testing immediately before transfusion in a bed-side like manner. This approach would overcome the sampling error observed in early sampling combined with culturing of bacteria and would, at least, prevent the transfusion of highly contaminated blood components leading to acute septic shock or even death of the patient. Flow cytometry has been demonstrated to be a rapid and feasible approach for detection of bacteria in platelet concentrates. The general aim of the current study was to develop protocols for the application of this technique under routine conditions. The effect of improved test reagents on practicability and sensitivity of the method is evaluated. Furthermore, the implementation of fluorescent absolute count beads as an internal standard is demonstrated. A simplified pre-incubation procedure has been undertaken to diminish the detection limit in a pragmatic manner. Additionally, the application of bacteria detection by flow cytometry as a culture method is shown, i.e., transfer of samples from platelet concentrates into a satellite bag, incubation of the latter at 37 degrees C, and measuring the contaminating bacteria in a flow cytometer.