Application of quantitative phase microscopy in microbiology for label-free imaging of bacteria
Permanent lenke
https://hdl.handle.net/10037/25087Dato
2022-03-15Type
Master thesisMastergradsoppgave
Forfatter
Abrar, AttiqaSammendrag
Bacteria are the planet’s oldest and the most common life forms. Bacteria have developed
alongside humans and are good and harmful to our health. Our bodies contain nearly ten
times the number of bacteria as human cells, and this natural microbiota is critical for
appropriate development, nutrition, and disease resistance. Unfortunately, we live in an
environment rich with bacteria that may cause a wide range of human diseases.[1]
Antimicrobial resistance (AMR) occurs when bacteria no longer remain vulnerable to the
antimicrobial for which it was responsive in the past. Around 33,000 Europeans die each
year from infections caused by (AMR) bacteria [2]. However, this number will be ten times
the current number of deaths by 2050 if AMR develops rapidly [2]. Furthermore, the lack
of new antibiotics in the development or trial phases is causing concern, particularly for
multidrug
resistant bacteria that manufacture extended-spectrum beta-lactamase
(ESBLs)
and carbapenems. Enterobacteriaceae (E. coli and Klebsiella pneumonia) is a family of
bacteria that belongs to the WHO’s priority one pathogen list.[3]
In this thesis, we tried to see if it is possible to see the potential difference between an
AMR and a nonAMR
bacterium. Also, we want to explore if it is possible to visualize
any difference between different AMR bacteria cells. And to see the bacteria, we need an
imaging technique suitable for imaging at high speed without the need for labels. The
next important fact is if the method is quantitative, we might be able to see the difference
in the quantitative parameters of the two types of bacteria cells. We had one such option in
our laboratory as Quantitative phase microscopy (QPM).
QPM is a noncontact,
noninvasive,
and label-free methodology that can quantify
various morphological and statistical parameters such as refractive index, height, dry mass,
surface area, volume, sphericity, mean associated with biological specimens.[4]
This thesis aims to obtain QPM images of three different bacteria species: E. coli,
Klebsiella pneumonia (K. pneumonia), and Staphylococcus aureus (S. aureus). The E. coli
bacteria have two different strains: E. coli(CCUG17620 and NCTC13441). One of them is
the wild type without an antimicrobial resistance gene, and the other is the nonwild
type
with an AMR gene and, in this case, will be an extended-spectrum
beta-lactamase
ESBLs.
Except for one bacteria sample, all others were with AMRgene.
The primary hypothesis was to investigate any difference in the morphology and
quantitative parameters obtained by the QPM images of four different bacteria. The longterm
aim was to examine if QPM can be used to image and classify bacteria. First,
a systematic characterization of the QPM system is performed in terms of spatial phase
sensitivity, temporal stability, spatial resolution, and defocus correction is done after phase
recovery. Next, QPM imaging of four different bacteria sampled is done to investigate
morphological parameter changes at a single wavelength. Further, the work is extended
with multispectral QPM of these bacteria samples to develop new biomarkers related to
them. In the future, the result can be fueled with the power of machine learning for the
classification of these bacteria samples based on the quantitative parameters extracted from
their QPM images.
Forlag
UiT Norges arktiske universitetUiT The Arctic University of Norway
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