Susceptibility of Antibacterial Chemicals on
Pseudomonas aeruginosa
Research performed by:
Clayton Brady
Health Science Biology Major
Tennessee Technological University
Introduction
Many diseases arise from bacteria that grow
resistant to the agents that are made to combat them.
Through new
research, scientists can develop new antimicrobial agents and antibiotics to
ensure the elimination of a bacterium for a limited period of time.
Pseudomonas
aeruginosa is responsible for 16% of nosocomial pneumonia cases, 12% of
hospital-acquired urinary tract infections, 8% of surgical wound infections,
and 10% of bloodstream infections.
Objective/Hypothesis
The
objective of my research is to determine if chemicals commonly found in the
antibacterial sprays we use so abundantly today can in fact render potentially
hazardous bacteria, such as Pseudomonas aeruginosa, non-viable.
I believe that the chemicals will have no effect
on Pseudomonas aeruginosa.
Materials
This experiment
required Petri dishes, a synthetic stock of Pseudomonas aeruginosa, an
inoculation loop, and a sterilizer (incinerator) for streaking the plates.
For my chemicals
I used Isopropyl Alcohol, 1 M Hydrochloric Acid, 5 % Hypochlorite Bleach, and
Vesphene.
In order to have
the bacteria to grow we needed an incubation device.
A ruler was
needed to measure the zone of inhibition around the discs.
Finally an
autoclave was required to sterilize the tools after use.
Methods
Using aseptic
techniques, the experiment began with taking an inoculating loop, sterilizing
it by way of heating it, and obtaining a sample of the bacteria being used.
The bacteria were
then exposed to discs dipped in each of the four chemicals. The dishes
were separated into quadrants for each of the four chemicals tested.
The bacteria were
given a day to grow and on the third day the zone of inhibition was observed
and measured for results.
Results
After
careful aseptic experimentation, I was able to kill Pseudomonas aeruginosa
with the antibacterial chemicals used in the experimental process.
Vesphene,
Isopropyl Alcohol and the 1 M Hydrochloric Acid were unable to kill the
bacteria.
Results Cont.
Discussion
The other
chemicals, perhaps effective on other types of bacteria, were ineffective
against Pseudomonas aeruginosa.
I originally
wanted to test household sprays against this bacteria, but after closer
examination I realized that the same chemicals are in most of the sprays.
In order to
continue my research I changed the sprays to specific chemicals commonly used
to sterilize equipment and tools in hospitals.
Project Summary
Pseudomonas
aeruginosa is an opportunistic
pathogen that engages in a plasmid exchange with other bacteria making it very
hard to kill because of its ability to build resistance to many cleaners and medicines.
By subjecting Pseudomonas
aeruginosa to chemicals found in many hospitals and often used to sterilize
equipment, I learned that many chemicals claiming to kill bacteria do not work
on Pseudomonas aeruginosa.
Conclusions
Bleach
(5% hypochlorite solution) was found to be an effective antibacterial agent
proving my hypothesis wrong.
Although
Isopropyl alcohol, Vesphene, and HCL (1M) may disinfect some bacteria it is not
effective as an antibacterial agent against Pseudomonas aeruginosa.
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