Electron Microscopy of Ebola Virus-Infected Cells

Scanning Electron Microscope Examination as an Alternative to Classical Microbiology in the Diagnostics of Catheter-Related Sepsis?

Central venous catheters are essential elements enabling the treatment of intensive care unit patients. However, these catheters are sometimes colonised by both bacteria and fungi, and thus, they may become a potential source of systemic infections-catheter-related bloodstream infections (CRBSI). The identification of the pathogen responsible for CRBSI is a time-consuming process. At the same time, the relationship between the quick identification of the pathogen and the implementation of targeted antibiotic therapy is of key importance for controlling the clinical symptoms of sepsis and septic shock in the patient. Quick diagnosis is of key importance to reduce morbidity and mortality in this group of patients. In our study, we attempted to create a catalogue of images of the most commonly cultured pathogens responsible for CRBSI. An FEI Quanta 250 FEG Scanning Electron Microscope (SEM) was used for measurements. SEM images obtained during the analysis were included in this study. Images of SEM are three-dimensional and comparable to the images seen with the human eye and are a tool used for research and measurement whenever it is necessary to analyse the state of the surface and assess its morphology. The method described in our study will not replace the current procedures recognised as the gold standard, i.e., pathogen culturing, determination of the count of microorganisms (CFU -colony forming units), and assessment of drug sensitivity. However, in some cases, the solution proposed in our study may aid the diagnosis of patients with suspected catheter-related bloodstream infections leading to sepsis and septic shock.

Atomic force microscopy and scanning electron microscopy as alternative methods of early identification of pathogens causing catheter-related bloodstream infections of patients in ICU

Introduction

Vascular catheters are an indispensable element of the therapy of patients in intensive care. Their use is associated with the possibility of complications, including infectious. According to various sources, the incidence of catheter-related bloodstream infections (CRBSIs) ranges from 0.1 to 22.7 per 1,000 catheter days.

Materials and Methods

The central venous catheter tip culture samples were collected from 24 patients with suspected catheter-related bloodstream infection, from three intensive care units (ICUs). The results of microscopic examinations: atomic force microscope (AFM) and scanning electron microscope (SEM) were compared with the results of microbiological analysis of the central venous catheter tip and blood collected from the catheter.

Results

The microscopic examination and microbiological analysis of both the blood and central venous catheter samples confirmed the presence of microorganisms in 16 cases (double positive result). Our study was conducted in a short period of time (up to 6 hours) and it gave an initial answer to the question about the type of microorganisms colonising the central venous catheter. In one patient the infection was not caused by removal of the central venous catheter. However, not all results were fully consistent within the two diagnostic methods. The colonisation of the central venous catheter with Pseudomonas aeruginosa and Staphylococcus epidermidis was microbiologically confirmed, but it was not confirmed by the microscopic examination of the sample collected from patient No. 20. However, the examination enabled preliminary assessment of the microorganism colonising the catheter, which may have caused the blood infection. It cannot be ruled out that Pseudomonas aeruginosa bacilli were grown on the catheter that came into contact with blood from another source of infection, e.g. the respiratory, nervous or urinary systems. Information on the presence of cocci-shaped bacteria forming characteristic clusters or rods may enable initial diagnosis of catheter-related bloodstream infection if it is accompanied by typical clinical symptoms. Alternative diagnostics also provides valuable information on the presence of biofilm, which is a factor hindering the body’s response to infection and penetration of antibiotics.

Conclusions

Our pilot study presents new diagnostic possibilities of microscopic imaging with the atomic force microscope (AFM) and scanning electron microscope (SEM) to identify pathogens on routinely used disposable medical devices, such as the central venous catheter. On the other hand, this range of diagnostics reveals the potential to constantly improve medical materials which come into direct contact with patients’ tissues. It is important to create a database of microscopic images, which would be a repeatable diagnostic pattern and fully correlated with the results of microbiological analysis, because it would facilitate initial quick diagnosis of a potential CRBSI.

Noninvasive Subcellular Imaging Using Atomic Force Acoustic Microscopy (AFAM)

We report an imaging approach applying the atomic force acoustic microscopy (AFAM), which has unique potential for nondestructive imaging of cell internal structures. To obtain high spatial resolution images, we optimized the significant imaging parameters, including scanning speeds, feedback configurations and acoustic frequencies of an AFAM system, to increase the amplitude of the acoustic signal and to stabilize the morphological signals. We also combined the acoustic amplitude and phase signals, and generated pseudo-color figures for better illustration of subcellular features such as pseudopodia, membranes and nucleus-like. The subcellular structural image atlas can describe nanoscale details of multiple samples and provide clearer images of the subcellular features compared to other conventional techniques. This study builds a strong basis of transmission AFAM for cell imaging, which can help researchers to clarify the cell structures in diverse biological fields and push the understanding of biology evolution to a new stage.