It
is the
tension 
between creativity and skepticism that has produced the stunning
and unexpected
findings of science. —Carl Sagan
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One of such microbial population is bacteria, they are
single celled organisms that lack a nucleus and membrane bound organelles.[i]Bacteria
may be killed instantly when exposed to a lethal agent. The rate of killing may
slow when the population has been greatly reduced due to the survival of a more
resistant strain of the bacteria.[ii]This
developed resistance is commonly referred to as antibiotic resistance, it is
when new strains of these bacteria have become resistant to many common
antibiotics, an illness that once took a week of antibiotic pills to cure may
exhibit no positive response to the antibiotics in the given period of time. Antibiotic resistance developed the ability of bacteria to
protect itself against the attack of an antibiotic. Antibiotic resistance occurs
when bacteria change in some way (ex. genetically) that reduces or eliminates
the effectiveness of the antibiotics.[iii]
The bacteria survive and continue to multiply which may cause more harm. Since
the first antibiotic was discovered, almost every type of bacteria has become
stronger and less responsive to antibiotic treatment.[iv]
These antibiotic-resistant bacteria can quickly spread to family members,
schoolmates, and other relations of the original host – threatening the
community with a new strain of infectious disease that is more difficult to cure
and more expensive to treat. If a bacteria strain is resistant to many drugs,
treating the infections it had caused can become difficult or even impossible.
In some cases, the illness can lead to serious disability or even death. Antibiotic overuse is the current explanation used to account the
occurrence of antibiotic resistance. The development
of antibiotic resistance is a classic case of natural selection with the
constant use of antibiotics being the selective pressure. Those bacteria which
did not have the necessary genetic mutations in combating antibiotics were
killed off, while those more resistant to the antibiotics survived, passing on
their more adaptable genes to future generations of bacteria, creating
antibiotic-resistant bacteria. In the course of natural selection, the mode of bacteria growth would affect its adaptability. Bacteria may grow planktonically or as biofilm. Planktonic bacteria are free-living organisms growing and suspending in a fluid environment.[v] No attached surface is needed for them, whereas biofilm bacteria are encased in the extracellular polysaccharide that they synthesize and adhered to a surface.[vi]This surface layer serves as a protection. In vitro experiments suggest that planktonic bacteria is more susceptible than biofilm bacteria of the same strain.10 Costerton further speculated that the more antibiotic-resistant characteristic of the biofilm bacteria also contributes to that bacteria bind or slow the transport of antibiotics, protecting the enclosed bacteria from exposure to lethal levels of antibiotics. If this is the case, then the decreased antibiotic susceptibility renders normal antibiotic chemotherapy ineffective in the treatment of bacterial infections. New treatments against antibiotic-resistant bacteria, as well as preventing further increase of antibiotic resistance among bacteria need to be discovered[vii]. One possible way that this may be done is to use ultrasound to enhance antibiotics by decreasing the viability of bacteria. As ultrasound has been extensively used in various medical applications, including medical diagnostic imaging and physiotherapeutic treatment, it can be considered safe for use in most patients.[viii] The bacteria strain that will be used in this experiment is Escherichia
coli (E. coli) DH5ά. They are rod-shaped, Gram-negative (cell walls
stain pink in colour) organisms with approximately 2 um in length and 0.8 um in
width. It is one of the main species of bacteria residing in the lower
intestines of mammals.[i]
E. coli was and is being used
extensively in microbiological experiments as a representative bacterium,
resulting in many accessible research papers and relatively abundant
information. In addition to that, E. coli
has a rapid rate of multiplication and are highly adaptable organisms that only
require a few nutrients to sustain life. These characteristics
were advantageous to the experiment.
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Enhancement of Antibiotic Action with an Application of
Ultrasound 29/04/2007 |
