scholarly journals Scanning Electron Microscope: A New Potential Tool to Replace Gram Staining for Microbe Identification in Blood Cultures

2021 ◽  
Vol 9 (6) ◽  
pp. 1170
Author(s):  
Gabriel Haddad ◽  
Sara Bellali ◽  
Tatsuki Takakura ◽  
Anthony Fontanini ◽  
Yusuke Ominami ◽  
...  

Blood culture is currently the most commonly used method for diagnosing sepsis and bloodstream infections. However, the long turn-around-time to achieve microbe identification remains a major concern for clinical microbiology laboratories. Gram staining for preliminary identification remains the gold standard. We developed a new rapid strategy using a tabletop scanning electron microscope (SEM) and compared its performance with Gram staining for the detection of micro-organisms and preliminary identification directly from blood cultures. We first optimised the sample preparation for twelve samples simultaneously, saving time on imaging. In this work, SEM proved its ability to identify bacteria and yeasts in morphotypes up to the genus level in some cases. We blindly tested 1075 blood cultures and compared our results to the Gram staining preliminary identification, with MALDI-TOF/MS as a reference. This method presents major advantages such as a fast microbe identification, within an hour of the blood culture being detected positive, low preparation costs, and data traceability. This SEM identification strategy can be developed into an automated assay from the sample preparation, micrograph acquisition, and identification process. This strategy could revolutionise urgent microbiological diagnosis of infectious diseases.

Author(s):  
Julien Goxe ◽  
Béatrice Vanhuffel ◽  
Marie Castignolles ◽  
Thomas Zirilli

Abstract Passive Voltage Contrast (PVC) in a Scanning Electron Microscope (SEM) or a Focused Ion Beam (FIB) is a key Failure Analysis (FA) technique to highlight a leaky gate. The introduction of Silicon On Insulator (SOI) substrate in our recent automotive analog mixed-signal technology highlighted a new challenge: the Bottom Oxide (BOX) layer, by isolating the Silicon Active Area from the bulk made PVC technique less effective in finding leaky MOSFET gates. A solution involving sample preparation performed with standard FA toolset is proposed to enhance PVC on SOI substrate.


Author(s):  
S. Basu

The imaging capabilities of the scanning electron microscope in conjunction with an energy dispersive x-ray spectrometer (SEM-EDX) allow both topographical and compositional displays that can be readily interpreted. Illustrative evidence of this type would be valuable in forensic determinations, since the associated techniques of image formation, chemical analysis and sample preparation are well understood and documented. Various methods of signal processing are also available, which allow intuitive, stylistic and synthetic interpretation of the image. Forensic applications of two such methods will be stressed in this report using a AMR 1000 SEM. These are deflection modulation (DM) or “Y-modulation” of secondary electron signal^ and x-ray dot mapping.


1995 ◽  
Vol 3 (5) ◽  
pp. 6-8
Author(s):  
Don Chernoff

Looking at samples in a scanning electron microscope often involves some type of sample preparation. The most common form of sample prep is coating the sample, usually with a heavy metal. The most common metal used for sample coating is gold. The need for coating samples is taken as a given by many people, but is it always necessary? To answer this question let us take a look at the reasons for coating a sample.


Minerals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 539 ◽  
Author(s):  
Gaia M. Militello ◽  
Elisa Sanguineti ◽  
Adrián Yus González ◽  
Federico Mantovani ◽  
Laura Gaggero

The aim of this work was to establish whether asbestos fibers homogeneously occur in the different fractions ground from naturally occurring asbestos lithotypes, and to calculate the contribution of fibers from each fraction to the overall concentration in the sample. Serpentinite, metabasalt, calc-schist, clay, debris material, and soil, were addressed. Grain size fractions below 20 mm were sieved at 2 mm and 0.106 mm; they were then were mechanically milled to obtain powders below 0.106 mm. The three powdered fractions were characterized using a scanning electron microscope coupled with energy dispersive spectroscopy following M.D. 06/09/94. The still in use (in some cases), Italian normative M.D. 161/2012 specifies that analyses must be performed on the <2 mm fraction and the concentration (mg/kg) correlated with the weight of the whole sample <20 mm. However, the fiber counts yielded asbestos concentrations 50–60% lower compared with total asbestos analyses according to the new R.P.D. 120/2017. Consequently, there is a need to standardize the normative worldwide regulations for the management of asbestos-containing materials, by re-evaluation of sample preparation and quantification of asbestos.


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