Introduction
In the last few years there has been
an increasing concern over issues such as food poisoning, drinking water
safety, and overall public health. Over the years food poisoning began
to appear more often and cause more drastic effects on humans. Several
scientists believe that Escherichia coli 0157:H7 is a major cause in many
cases of food poisoning (MaCdonald, 1993).
Escherichia
coli is recognized as a bacteria which is found inside the human intestines
living in a symbiotic relationship. Escherichia Coli has also served as
sign of fecal contamination in water, food, etc. In the last decade Escherichia
coli 0157:H7 emerged as a food-borne microbe. Every year 20,000 people
are sick because of Escherichia coli 0157:H7 each year. Of those 20,000
people more than 200 people die every year (center for Disease Control
and prevention, 1993). Escherichia coli can survive with or without oxygen
and is not very meticulous in it’s nutritional requirements.
Certain strains
of Escherichia coli may cause hemolytic uremic syndrome (Robson, 1993).
Symptoms of this disease include severe stomach pain, possible fever, internal
bleeding, and severe diarrhea. These symptoms usually occur within 3 or
4 days of ingestion (Robson, 1993). This disease posses a greater health
threat to children and the elderly. During the first six days of Escherichia
Coli 0157:H7, stool cultures detect the organism in most patients; however
after the initial six day period only on-third of the patients infected
may be detected by culture. It may also become extremely difficult to identify
the organism which is causing the infection after the initial six day period
(Tarr, 1990). Serious complications may also arise if the symptoms go untreated.
Escherichia Coli was thought
to be transmitted by food through ingestion of improperly cooked meat.
However the pathogen can be spread through vegetables and fruits, because
Escherichia coli may be living in the fertilizer used in the production
of those same fruits and vegetables (MaCdonald, 1993). Another method by
which Escherichia coli is spread is the improper disaffection of
kitchen utensils which were used in the preparation of uncooked meat. To
control this problem several anti-bacterial products such as sanitizers
and disinfectants are successfully being used in the prevention of the
spread of Escherichia Coli.
This leads us to the
purpose of this experiment. The goal of this experiment is to find which
cleaner is most effective against the spread of Escherichia Coli.
Disinfectants are chemical
agent which kill pathogens on contact (Wolfe, 1997). They are classified
according to the specific action the perform on different forms of
microorganisms. Bactericides kill vegetative microorganisms which will
be the class tested in this experiment.
Chemical agents
can kill cells in many different ways. On of these ways is protein coagulation.
Most of the proteins in a cell are enzymatic, and exist in a dispersed
state within the cell. Disinfecting chemicals, which cause these proteins
to coagulate, make the cell non-functional and thus killing it.
Disruption of the cell membrane
is another way chemical agents affect cells. The cell membrane acts as
a selective barrier allowing some substances to be absorbed into the cell
and keeps other substances out. Substances which concentrate at the cell
membrane may alter the physical and chemical properties of the cell membrane,
preventing its normal function, and thus killing the cell.
Disinfectants
can also work by removing free sulphydrl groups. Many of the enzyme proteins
in a cell contain cysteine (amino acid) and have side chains terminating
in sulphydril groups. These enzymes can not function unless the sulphydryl
groups remain free. If the sulphydryl groups are tied down, for example
by an oxidizing agent, widespread damge to the cell occurs.
Cleaning agents were picked
out which advertise anti-bacterial properties. Palmolive anti-bacterial
cleaner made by Colgate-Palmolive company was one of them. Palmolive
was found to contain trisclosan which is a bacteriostat agent. Triclosan
has been shown to provide protection against many types of bacteria including
Escherichia Coli (Colgate-Palmolive 1997). Comet Liquid gel cleaner is
another disinfectant. It contains sodium hypochlorate which is known
to be effective as an anti-bacterial cleaner (Comet, 1997)
This experiment
is designed to test the effectiveness of the two name brand cleaners against
the spread of Escherichia Coli bacteria. I hypothesize that Palmolive
anti-bacterial cleaner will kill of more Escherichia Coli bacteria than
Comet liquid gel cleaner.
