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

Abstract

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.

Keywords: CRBSI; SEM; catheter-related sepsis; clinical microbiology; intensive care unit; scanning electron microscope.

Figure 1

Scanning electron microscopy (SEM) images of reference pathogens: Gram-positive cocci: (A) Staphylococcus aureus, (B) Staphylococcus epidermidis; Gram-positive cocci—streptococci: (C) Streptococcus parasanguinis; Gram-positive enterococci: (D) Enterococcus fecalis; Gram-negative bacilli (E) Klebsiella pneumonie, (F) Escherichia coli, (G) Pseudomonas aeruginosa; yeast-like fungi of the Candida genus: (H) Candida dubliniensis, (I) Candida albicans.