· web viewantibiotic resistant bacteria are a prominent issue in modern day society and are...

Antimicrobial copper

By Jason Ren

Contents Page:Abstract……………………………………………………………………………………………………3Aim…………………………………………………………………………………………………………..3Background Information……………………………………………………………………………3Equipment………………………………………………………………………………………………17Hypothesis………………………………………………………………………………………………17Variables…………………………………………………………………………………………………18Controls…………………………………………………………………………………………………..18Procedure………………………………………………………………………………………………..18Risk assessment……………………………………………………………………………………….26Results……………………………………………………………………………………………………..27Calculations..………………………………………………………………………….…………………28Analysis……………………………………………………………………………………………...……30Discussion………………………………………………………………………………………………..34Conclusion………………………………………………………………………………………………..39Bibliography……………………………………………………………………………………………..40Appendix…………………………………………………………………………………………………..43

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Date: 9 June- 25 June

Abstract:

Antibiotic resistant bacteria are a prominent issue in modern day society and are

becoming more prevalent in many clinical environments such as hospitals.

Infections caused by antibiotic and non-antibiotic resistant bacteria are often

spread by contact surfaces such as handrails, door handles, taps, and toilet seats.

Copper surfaces have been suggested to have antimicrobial properties, killing up

to 90% of bacteria and has been proposed as an alternative to stainless steel and

plastic surfaces. Cells exposed to copper surfaces have been shown to suffer

extensive membrane damage and showed loss of cell integrity.

Aim:

To determine if copper surfaces can be used as an antimicrobial agent to limit

bacterial growth and if it has practical applications in clinical healthcare

environments such as hospitals

Background Information:

Bacterial cell structure

First seen under a microscope in 1676 by Anton Van Leeuwenhoek, bacterial

cells are much smaller then plant or animal cells. As microscope technology has

improved, scientists have come to understand bacterial cell structure in more

depth. A bacterial cell is made up of different parts such as the capsule, cell wall,

plasma membrane and the nucleoid1. The cell membrane is the semipermeable

membrane that surrounds the cytoplasm of a cell and has numerous roles. These

roles encompass a variety of functions such as energy generation and transport

of solutes as well as housing many enzyme systems2. The plasma membrane is

predominantly composed of phospholipids and proteins. Within the cell

membrane are the cytoplasm, ribosomes, mesosomes, plasmid and the nucleoid3.

1 Structure and Function of Bacterial Cells. 2015. Structure and Function of Bacterial Cells. [ONLINE] Available

at:http://textbookofbacteriology.net/structure.html. [Accessed 25 June 2015]

2 BBC - GCSE Bitesize: Plant and animal cells. 2015. BBC - GCSE Bitesize: Plant and animal cells. [ONLINE] Available at:http://www.bbc.co.uk/schools/gcsebitesize/science/add_edexcel/cells/cells2.shtml. [Accessed 25 June 2015]3 Bacterial DNA – the role of plasmids | Biotech Learning Hub. 2015.Bacterial DNA – the role of plasmids | Biotech Learning

Hub. [ONLINE] Available at:http://biotechlearn.org.nz/themes/bacteria_in_biotech/bacterial_dna_the_role_of_plasmids.

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The cytoplasm is where metabolic processes necessary for life occur. Ribosomes

are sites of protein synthesis, i.e. they are involved in the manufacture of

proteins. The nucleoid is the area that contains the cell’s DNA. Mesosomes play a

role in cellular respiration, which is a process that breaks down food to release

energy. The plasmid contains extrachromosomal genetic material. These genes

are usually not necessary for the bacterium’s day-to-day survival. Instead, they

help the bacterium overcome, for example, situations where it is exposed to

antibiotics. In these instances many plasmids, contain genes that when expressed

make the bacterium resistant to antibiotics. Other plasmids can also contain

genes that help the bacterium kill other bacteria. Without these important

structures such as ribosomes and mesosomes, the bacterial cell cannot function

properly and may quickly die.

Antibiotics

Antibiotics are medicines used to treat diseases or infections cause by bacteria.

Antibiotics differ in how they work and the types of bacteria they work against.

The main classes of antibiotics include: penicillins, cephalosporins4, macrolides,

aminoglycosides and fluoroquinolones5. Cephalosporins and penicillins kill

bacteria by destroying bacterial cell walls. Macrolides and aminoglycosides work

by binding to a specific subunit of ribosomes in susceptible bacteria, inhibiting

the formation of bacterial proteins6. This action in most organisms inhibits cell

growth, however in high concentrations it can cause cell death. The protein that

the antibiotic aims to inactivate is sometimes referred to as the target protein7.

Fluoroquinolonies can cause sever side effects in rare cases, and are therefore

[Accessed 25 June 2015]

4 Antibiotics Causes, Symptoms, Treatment - Types of Antibiotics - eMedicineHealth. 2015. Antibiotics Causes, Symptoms,

Treatment - Types of Antibiotics - eMedicineHealth. [ONLINE] Available

at:http://www.emedicinehealth.com/antibiotics/page2_em.htm. [Accessed 25 June 2015]

5 http://pharmaxchange.info/press/2011/05/mechanism-of-action-of-quinolones-and-fluoroquinolones/ (Akul, M.

(2011). “Mechanism of Action of Quinolones and Fluorquinolones”. 10th May)

6 Overview - Biology Online. 2015. Overview - Biology Online. [ONLINE] Available at:

http://www.biology-online.org/articles/aminoglycoside.html. [Accessed 13 August 2015].

7 What are antibiotics and how do they work? | NPS MedicineWise. 2015.What are antibiotics and how do they work? | NPS MedicineWise. [ONLINE] Available at: http://www.nps.org.au/medicines/infections-and-infestations/antibiotics/for-individuals/what-are-antibiotics-and-how-do-they-work. [Accessed 25 June 2015]

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not used for regular treatment of bacterial infections. They are used for more

resistant strains of bacteria and work by blocking DNA replication pathways of

bacteria thereby inhibiting bacterial replication.

Antibiotic resistant bacteria

Antibiotic medications are used to kill harmful bacteria, which can cause disease

and illness. They have made a major contribution to human health, however,

some bacteria have become resistant to commonly used antibiotics, an example

being Methicilim-resistant Syaphylococcus Aureus, better known as MRSA8.

Antibiotic resistance is a current public health problem and can cause serious

widespread disease. Some bacteria are naturally resistant to some antibiotics.

For example benzyl penicillin has very little effect on most organisms found in

the human digestive system. The first step in the emergence of resistance in

bacteria is a genetic change9. There are various ways this can happen; two

methods include spontaneous mutation in the bacterium’s DNA and transfer of

antibiotic-resistance genes. Many antibiotics, e.g. Penicillin, work by inactivating

an essential bacterial protein. Not only can a genetic change can remove that

protein, mutations in the target protein can prevent the antibiotic from binding,

or if its does bind; prevent it from inactivating the target protein10. To prevent

the antibiotic from binding with the target, some bacteria change the structure of

the target so that the antibiotic can no longer recognize it or bind to it. Genetic

change can also lead to increased production of the target enzyme of an

antibiotic, so that there are too many for the antibiotic to inactivate. Alternatively

the bacterium may produce an enzyme that inactivates antibiotics. An example is

an enzyme called beta-lactamases that “inactivate” penicillin. In addition, to stop

antibiotics form entering the cell, the bacterium may alter the permeability of its

cell membrane. The second method for a bacterium to gain resistance is by the

transfer of an antibiotic-resistance gene from one bacterium to another

8 Antibiotic resistant bacteria | Better Health Channel. 2015. Antibiotic resistant bacteria | Better Health Channel. [ONLINE] Available at:http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Antibiotic_resistant_bacteria. [Accessed 25 June 2015]9 How bacteria become resistant. 2015. How bacteria become resistant. [ONLINE] Available at:

http://www.abc.net.au/science/slab/antibiotics/resistance.htm. [Accessed 13 August 2015].

10 How do bacteria become resistant to antibiotics? - HowStuffWorks. 2015. How do bacteria become resistant to antibiotics? - HowStuffWorks. [ONLINE] Available at: http://science.howstuffworks.com/environmental/life/cellular-microscopic/question561.htm. [Accessed 13 August 2015].

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bacterium. Antibiotic resistance not only spreads due to the transfer of

antibiotic-resistance genes, but through the movement of bacteria form one host

to another, either indirectly or directly. In humans, when a course of antibiotics

is taken there is always the chance that there will be some bacteria with

resistance, as well as the fact that often the full course of antibiotics is not taken.

Those not killed are now free to multiply without any competition form weaker

strains. Friendly bacteria can also be wiped out by antibiotics, which would

otherwise compete with the resistant strain for resources.

In modern day society, bacteria are gradually increasing its resistance to

antibiotics. The world currently has a demand for a new antibiotic, but finding

one is proving to be a great challenge. However copper may be the key to killing

antibiotic resistant bacteria such as MRSA as well as improving general health by

limiting bacteria growth.

What is copper?

Copper (Cu) is one of the best electrical conductors of metals. Light red in colour

and easily oxidized to a green hue, copper can be formed and drawn to serve

many purposes from water pipes and circuit boards to jewellery and

architecture, and in the case of this project to possibly replace common contact

surfaces made out of materials such as plastic, to limit bacteria growth, in

hospitals.

Possible property of copper that kills bacteria

Properties of copper thought to kill bacteria include its high conductivity as well

as the release of copper ions when contact between bacteria and the metallic

surface occurs.

What differentiates copper from antibiotics?

In the context of killing bacteria, copper does not kill bacteria via “conventional”

methods used by antibiotics. In stead it uses other methods such as in causing

holes to appear in the cell membrane. The antibiotic penicillin causes a similar

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reaction in bacteria to kill bacteria. However it does so by targeting proteins and

enzymes in the membrane. Resistance to this action has already emerged and

can be spread easily. On the other hand a proposed method of how copper

creates holes is that copper essentially “Short circuits” the cell membrane11. This

is an example of how copper attacks bacteria from “another direction”, i.e. it kills

bacteria in in a different way, when compared to antibiotics. Another, perhaps

more important factor that differentiates copper form antibiotics, is that copper

can kill drug resistant “superbugs”. In other words, copper can kill some

antibiotic resistance bacteria. Studies conducted have shown that copper

surfaces can kill E.Coli, Clostridium difficile, Influenza A, Adenovirus, and

perhaps the most infamous of them all Methicillin-resistant Staphylococcus

aureus, better known as MRSA. In 2004 the University of Southampton research

team conducted an experiment that demonstrated copper inhibiting the growth

and replication of MRSA. This study found that “Faster antimicrobial efficacies

were associated with higher copper alloy content”, and that “stainless steel did

not exhibit any bacterial benefits”. Furthermore, in 2008, the United States

Environment Protection Agency (EPA)12, after evaluating a wide body of

research, granted a registration approval that certified “copper alloys kill more

that 99.9% of MRSA within two hours”13.

Proposed methods of how copper kills bacteria

Research has been conducted in the area of how copper kills bacteria, however

results are not certain and are subject to disagreement. The most conclusive and

evidence backed property of copper that kills bacteria is through contact killing.

Although the mechanism of contact killing is still not fully understood, recent

studies suggest that copper surfaces kill bacteria by a three-pronged attack:

damage of the bacterial membrane, extensive intracellular damage, and DNA

degradation. The sequence of these events is still under debate and may be

11 The Science behind Antimicrobial Copper. . 2015. The Science behind Antimicrobial Copper. . [ONLINE] Available at:http://antimicrobialcopper.com/us/scientific-proof/how-it-works.aspx. [Accessed 25 June 2015]12 Killing of Bacteria by Copper Surfaces Involves Dissolved Copper . 2015.Killing of Bacteria by Copper Surfaces Involves Dissolved Copper . [ONLINE] Available at:http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2893463/. [Accessed 25 June 2015]13 Antimicrobial properties of copper - Wikipedia, the free encyclopedia. 2015. Antimicrobial properties of copper - Wikipedia, the free encyclopedia. [ONLINE] Available at: https://en.wikipedia.org/wiki/Antimicrobial_properties_of_copper. [Accessed 13 August 2015].

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different depending on the microorganism. For many organisms, copper as a

trace element is an essential nutrient. Furthermore, in respiration, copper serves

as a cofactor and is thus needed for aerobic metabolism. However, when copper

is in excess and in high concentrations, it is highly toxic. Every cell’s membrane

including both multicellular and single celled organisms like bacteria contains a

stable electrical micro-current, often called “trans membrane potential” and is

essentially the voltage difference between the inside and outside of a cell. It is

suspected that when bacterium comes into contact with a copper surface, a

short-circuiting of the current in the cell membrane can occur. This may be due

to the high conductivity of copper. This short-circuiting weakens the membrane

and creates holes. Another method that holes may be opened in the membrane is

through the interaction of copper ions with lipids causing their peroxidation14.

The opening of holes in the cell membrane can compromise the integrity of the

cell, which can cause the leakage of essential solutes resulting in a desiccating

effect. Once the cell membrane has been breached, there is essentially an

unopposed stream of copper ions entering the cell. It is at this stage that most of

the damage is done to the cell. Copper readily catalyses reactions that result in

the production of hydroxyl radicals through Haber-Weiss and Fenton reactions.

Hydroxyl radicals can damage virtually all types of macromolecules; some

examples include nucleic acids, amino acids and lipids. The formation of radicals

can also inactivate viruses. Highly reactive oxygen intermediates causes lipid

peroxidation and oxidation of proteins. In other words, in this process, lipids and

proteins are degraded by oxidation. Copper ions inactivate proteins by damaging

Fe-S clusters as well as by replacing the respective metals in metalloproteins

with copper. Copper ions may also disrupt enzyme structures and functions by

binding to sulphur. To put it simply, copper ions entering cells puts vital

processes inside the cell in danger. Copper can obstruct cell metabolism as well

as stopping enzymes inside the cell from performing vital functions. This occurs

when the copper ions make molecular bonds with these enzymes. For

Escherichia coli (E-Coli) in particular, copper damage to the respiratory chain in

14 Antimicrobial metallic copper surfaces kill Staphylococcus haemolyticus via membrane damage. 2015. Antimicrobial

metallic copper surfaces kill Staphylococcus haemolyticus via membrane damage. [ONLINE] Available

at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3426407/. [Accessed 25 June 2015]

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E-Coli cells has been linked with impaired cellular metabolism. Recently in 2014,

live/dead staining performed in various studies indicated that cell membrane

damage occurred in cells on copper surfaces but not steel surfaces. These

findings suggest that metallic copper does not kill via DNA damage. In contrast,

membranes are most likely the Achilles heel of cells exposed to copper. Although

copper may not kill via DNA damage it still may degrade DNA when “attacking”

cells.

Further studies of antimicrobial properties of copper found that the surface

structure of copper as well as the environment that it was in affected the rate at

which bacteria was killed15. The importance of the release of copper ions in the

killing of bacteria implies that the surface structure of a copper surface is a factor

in the rate at which bacteria is killed. A study performed by the National Centre

for Biotechnology Information (NCBI) found that contact killing of bacteria in

copper is essentially supressed if bacterial contact with metal is prevented16.

This is an important issue as over time, copper corrodes to develop a green

verdigris (or patina). This layer of verdigris may inhibit the ability of copper to

kill bacteria. On the other hand, the more contact a copper surface has with

bacteria, the higher the rate at which bacteria is killed. A possible explanation for

this is that the more contact the copper surface has with bacteria the faster it

corrodes. Faster corrosion rates have been correlated with faster inactivation of

microorganisms. The rational behind this is that a higher corrosion rate means a

increased availability of cupric ions (copper ions with a +2 charge), which is

believed to be one of the factors responsible for copper’s antimicrobial action.

Bacteria-metal contact can also be prevented by a build up of dead bacteria. This

dead bacteria can act as a barrier between the “healthy and alive” bacteria and

the copper surface. As discussed above, if bacterial-metal contact is prevented

then the killing of bacteria is supressed. However, the barrier of dead bacteria 15 Surface structure influences contact killing of bacteria by copper. 2015.Surface structure influences contact killing of bacteria by copper. [ONLINE] Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4082706/. [Accessed 25 June 2015]16 Contact Killing of Bacteria on Copper Is Suppressed if Bacterial-Metal Contact Is Prevented and Is Induced on Iron by

Copper Ions. 2015. Contact Killing of Bacteria on Copper Is Suppressed if Bacterial-Metal Contact Is Prevented and Is

Induced on Iron by Copper Ions. [ONLINE] Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3623184/.

[Accessed 13 August 2015].

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will eventually be broken down and new bacteria will come into contact with the

copper surface. Dead bacteria can also be removed by cleaning the copper

surface. Furthermore, dry copper surfaces killed bacteria faster and in larger

numbers then moist copper surfaces. An explanation is that the intake of copper

ions is faster form dry copper than from moist copper17. In addition, moist

surfaces promote bacterial growth, whereas dry surfaces do not.

Bacterial growth

Bacterial growth is generally dependent on the existence of water, however

there are some parameters for optimum bacterial growth.

1. Supple of suitable and retrievable nutrients- the nutrients present should

be in a form that allows the bacterial cell to passively or actively intake

them18

2. Existence of water- as mentioned above, bacterial growth is strongly

dependent on water. Dry surfaces doe not promote bacterial growth

3. Presence of a source of carbon or other forms of energy- all life forms that

exist take up some form of energy to survive. For example,

microorganisms that perform photosynthesis and receive primary energy

from sunlight, require the gas carbon dioxide as a carbon source

4. Existence of appropriate temperature- different microorganisms have

different requirements regarding temperature for optimum growth. E-

Coli falls into the category of mesophiles and has an optimum growth

temperature of 370C. Mesophiles are bacteria that can grow and divide

between 100C-450C19

5. Appropriate pH of the environment- most microorganisms including E-

Coli, grow best when the pH is around 7(neutral pH)

Methods of sterilisation and disinfecting

17 Bacterial Killing by Dry Metallic Copper Surfaces . 2015. Bacterial Killing by Dry Metallic Copper Surfaces . [ONLINE] Available at:http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3028699/. [Accessed 25 June 2015].18 New Page 2. 2015. New Page 2. [ONLINE] Available at: http://classroom.sdmesa.edu/eschmid/Lecture4-Microbio.htm. [Accessed 13 August 2015].19 Growth Requirements of E. coli. and Auxotrophs - Video & Lesson Transcript | Study.com. 2015. Growth Requirements of E. coli. and Auxotrophs - Video & Lesson Transcript | Study.com. [ONLINE] Available at: http://study.com/academy/lesson/growth-requirements-of-e-coli-and-auxotrophs.html. [Accessed 25 June 2015]

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Disinfecting is a process of reducing or eliminating harmful microorganisms.

Sterilisation refers a chemical or physical process that completely removes or

destroys all viable microorganisms20. The destroying of all microorganisms is the

main difference between disinfecting and sterilizing. Disinfecting can be

performed by application of bleach, detergents and alcohols. Alcohols with a

concentration of 70% can be used to quickly and efficiently disinfect surfaces21.

In contrast to external surfaces, internal surfaces such as the inside of a pipe may

be harder to reach and may take longer to clean. Due to the rapid evaporation of

alcohol, extended contact times are more difficult to achieve. Consequently,

submersion of the item in alcohol is suggested when trying to clean internal

surfaces with alcohol. This property of alcohol makes it useful for cleaning

objects such as copper and PVC tubing. Heat is both a method that can be use to

disinfect or sterilize. However, using heat to disinfect copper and plastic surfaces

would not be a practical method in this project. In contrast, the use of heat is

useful to sterilize inoculation loops. In a process called flaming, inoculation loops

are sterilised before and after the retrieval of bacteria. It is also recommend that

when transferring bacteria from a slope to an external location such as a broth,

the mouth of the container, if it is made of glass, should be flamed prior to and

after the bacteria is transferred22.

Aseptic technique in microbiology

Some practices of microbiology relevant to this experiment include setting out

the workspace, inoculating agar plates and flaming inoculation loops and necks

of bottles.

Setting out the workspaces

20 2.1 Cleaning, Disinfection & Sterilisation . 2015. 2.1 Cleaning, Disinfection & Sterilisation . [ONLINE] Available

at:http://www.health.qld.gov.au/EndoscopeReprocessing/module_2/2_1.asp. [Accessed 25 June 2015]

21 Disinfectants and Sterilization Methods | Environmental Health & SafetyEnvironmental Health & Safety | CU-Boulder .

2015. Disinfectants and Sterilization Methods | Environmental Health & SafetyEnvironmental Health & Safety | CU-Boulder .

[ONLINE] Available at:http://ehs.colorado.edu/resources/disinfectants-and-sterilization-methods/. [Accessed 25 June

2015]

22 Aseptic techniques | Nuffield Foundation. 2015. Aseptic techniques | Nuffield Foundation. [ONLINE] Available at:http://www.nuffieldfoundation.org/practical-biology/aseptic-techniques. [Accessed 25 June 2015]

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- To reduce the chance that air might be disturbed by a draught, all

windows and doors should be closed

- The experiment should only begin once all apparatus and materials are

within immediate reach

Inoculating agar plates

- Inoculation and transfer of microbes should be conducted under a

laminar flow

- A laminar flow is where air currents are drawn upwards, this can be

achieved by working close to a Bunsen burner flame

- Transfer of microbes between surfaces should be conducted as quickly as

possible with the agar plate being open to the air for least amount of time

possible

Flaming inoculation loops and necks of bottles

- Inoculation loops should be flamed prior to and after use

- The loop should be flamed by passing the wire through the hottest region

of the flame, and held in the flame until the wire is red-hot. All parts of the

wire should flamed. The image below is a visual representation of the

flaming process

- After the loop is flamed allow it to cool for a few seconds in the air before

using it immediately

- Note: The flaming procedure should heat the wire of the loop gradually, as

after use, it will most likely contain some sort of residue which may

splutter on rapid heating. This may result in small particles of the residue

becoming airborne.

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- Flaming of neck of bottles aims the ensure that no microorganisms

contaminate the medium or culture by entering the mouth of the

container

- Passing the mouth of the bottle through a flame produces a convection

current away from the opening, which helps prevent contamination

Calculating CFU/ml

Colony Forming Units per ml (CFU/ml) can be used as a method to measure

viable bacterial or fungal cells23. It is important to note that CFU only measures

viable cells. Viable cells can be defined as the number of cells in a given area of

volume that are thriving24. CFU/ml can be calculated using the formula:

CFU/ml= (number of colonies)/(Volume of culture plated x Dilution factor)

The number of colonies can be found by counting the number of colonies in the

culture plate, i.e. an agar plate. The dilution factor is essentially a measure of how

diluted a solution is and is usually measured by “factors of ten”25, for example, a

solution would be diluted “by a factor of ten or a hundred”, rather than a factor of

50.

The dilution factor can be calculated by using the formula

C1V1=C2V2

Where:

V1= Volume of stock solution needed to make new solution

C1= Concentration of stock solution

V2= Final volume of new solution

23 efinition of viable cell count by Medical dictionary. [ONLINE] Available at: http://medical-

dictionary.thefreedictionary.com/viable+cell+count. [Accessed 25 June 2015]

24 Bio-Resource: CFU: Colony Forming Unit & Calculation. 2015. Bio-Resource: CFU: Colony Forming Unit & Calculation. [ONLINE] Available at:http://technologyinscience.blogspot.com.au/2011/11/cfu-colony-forming-unit-calculation.html#.VYFXGEKaK2R. [Accessed 25 June 2015]25 Dilutions: Explanations and Examples of Common Methods | Quansys Biosciences. 2015. Dilutions: Explanations and Examples of Common Methods | Quansys Biosciences. [ONLINE] Available at:http://www.quansysbio.com/dilutions. [Accessed 25 June 2015]

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C2= Final concentration of new solution, i.e. how much it is diluted by. For

example if C2=0.1 then new solution would be diluted by a factor of 10.

Actual studies conducted

Various studies have been conducted by reliable sources such as governments

and reputable academic journals in the area of antimicrobial copper. Of the

studies researched, all came to a conclusion, which contained essentially the

same theory, that copper inhibits the growth of bacteria. A study published by

The Journal of Hospital Infection, demonstrated that installing copper surfaces in

healthcare environments reduces the risk of acquiring HCAI26. Another extensive

study published by The University of Chicago Press on behalf of The Society for

Healthcare Epidemiology of America found that copper alloys containing more

than 60% copper reduced amount of bacteria on solid surfaces in an outpatient

environment by 99.9% within 2 hours27. This study also found that copper

surfaces were able to diminish bacteria levels to below those considered a risk

for patients for acquiring an infection. The study was conducted by replacing

common touch surfaces on phlebotomy chairs in an outpatient infectious disease

clinic such as armrests and plastic trays with a copper alloy metal containing

90% copper and 10% nickel. A total of 437 patients using the chairs over a 15-

week study period were recorded. The results showed that copper surfaces

reduced the bacterial population present on the arm surfaces and trays. A

reduction of 90% on copper arm rests for total aerobic bacteria and an 88%

median reduction on copper trays was observed. This study did take into

account outliers with 17 data points being removed from the analysis. Some data

was removed due to no patients using a particular chair on that day and other

data was removed due to sample damage.

26 DEFINE_ME_WA. 2015. DEFINE_ME_WA. [ONLINE] Available at:http://www.journalofhospitalinfection.com/article/S0195-6701(12)00165-X/abstract. [Accessed 25 June 2015]27 2015. . [ONLINE] Available at: http://www.asminternational.org/eNews/copper_hospchair.pdf. [Accessed 14 August 2015].

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Amount of bacteria (CFU/100cm2) on two phlebotomy chairs sampled in the experiment

Another study which has its initial results presented at the World Health

Organization’s first International Conference on Prevention and Infection

Control (ICPIC) in Geneva, Switzerland on 1 July 2001, showed that from a

comprehensive, multi-site clinical trial in the United States, copper surfaces in

intensive care unit rooms demonstrated a 40.4% reduction in the risk of

acquiring a hospital infection28. Researches in the three hospitals involved in the

clinical trial; Memorial Sloan Kettering Cancer Centre in New York, the Medical

University of South Carolina, and the Ralph H. Johnson VA Medical Centre,

replaced commonly touched surfaces such as bed rails, tray tables, IV poles and

nurse call buttons with antimicrobial copper versions. The rooms with copper

surfaces demonstrated a 97% reduction in surface pathogens, which is the same

level achieved by terminal cleaning, a process conducted after a patient vacates a

room. A study conducted in the United States over four-years has shown that the

use of antimicrobial copper surfaces in hospital rooms can reduce the number of

28 [ONLINE] Available at: http://web.b.ebscohost.com.newington.idm.oclc.org/ehost/pdfviewer/

pdfviewer?sid=dbaebc08-7ad3-4341-910c-3ae3a0f24740%40sessionmgr198&vid=1&hid=128. [Accessed

18 August 2015].

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health care acquired infection (HAIs) by 58% when compared to rooms without

copper surfaces29. The study also confirmed that antimicrobial copper surfaces

could continuously kill 83% of bacteria that cause HAIs with two hours,

including drug resistant “superbugs”. The idea that copper inhibits bacterial

growth is further backed in a cross-over study published by the US National

Centre for Biotechnology Information, which found that copper surfaces in a

medical ward harboured between 90% and 100% lower median numbers of

microorganisms. Among these studies, other extensive studies have also been

conducted in Japan, South Africa, Chile, and United Kingdom & Ireland. While

these studies have been conducted with different aims and methods, all of them

show evidence that copper can inhibit bacterial growth.

Application of copper in clinical environments

Worldwide, HAIs are a major and growing problem. In Australia around 9000

people die form health related infections each year. While copper has been

linked with antimicrobial properties, recent studies have concluded that copper

can reduce the risk of acquiring a health care related infection. The reduction of

picking up HAIs would save lives and cut healthcare costs. The primary

installation of copper in hospitals would most likely be more expensive than

traditional surfaces such as plastic. However, studies have shown that some

hospitals are underfunded to deal with infection. According to the World Health

Organization, healthcare facilities around the world, seven million infections

occur every year and cost more that $80 billion globally. By reducing the risk of

infections, overtime the cost of installing copper surfaces would be offset by the

costs saved when risk of infections are reduced, which is to not exclude the fact

that many lives would be saved in the process. Antimicrobial copper surfaces

and products are currently being manufactured worldwide. An increasing

number of aged care facilities, medical clinics and hospitals are employing the

use of these copper products as part of various infection control strategies.

Equipment:29 [ONLINE] Available at: http://web.b.ebscohost.com.newington.idm.oclc.org/ehost/pdfviewer/pdfviewer?

sid=1e7802be-ffc9-492d-b95d-7948c4b7c0fb%40sessionmgr110&vid=1&hid=128. [Accessed 18 August 2015].

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Item Number requiredCopper Tubing (15cm) 1Stainless Steel Tubing (15cm) 1PVC Tubing (15cm) 1Agar Plates 27Beakers (250ml) 12Beakers (1L) 2Retort Stand with Boss Head Clamp 3Distilled Water 2LSterile Swabs Pack of 10070% Alcohol Solution 500mlStopwatch 1Sharpie 1Sticky Tape 1 rollPencil 1Ruler (15cm) 1Thermometer 1Scissors 1Glass Stirring Rod 1Detergent 50mlGlass Jar (Height>15cm, Diameter>8cm) 1Pipets 20Bacteria E-ColiLatex gloves 4Safety glasses 1Glass pipette (6ml) 1Glass pipette (1ml) 1Bunsen burner 1Matches 1 boxInoculation loop 2

Hypothesis:The copper in comparison to the stainless steel and PVC should have a much

lower CFU/ml count when the agar plates are cured and the bacteria allowed to

grow. This would not only show that copper is a effective antimicrobial agent, it

would show that in comparison with commonly used materials in hospitals such

as plastic and stainless steel surfaces, copper is more effective in killing bacteria

which may reduce the risk of healthcare- associated infections (HAI). This

property of copper would be a reason why it would have practical applications in

clinical environments such as hospitals in reducing HAIs.

Variables:

Controlled Variables

- Temperature of distilled water

- Time the tubing is allowed to set in the bacterial solution

- Time intervals at which swabs are taken at

Independent Variables

17

- Concentration of the bacterial solution

Dependent Variables

- Amount of viable bacteria on the three types of surfaces

Controls to be tested:

- Bacterial solution without any contact with external surfaces such as

swabs30

- Swabs themselves (This is to see how sterile they are)

Procedure:

Initial Preparation/sterilization of tubing:

1. Mark a horizontal line 5cm from the bottom of each tube, see fig.1 for

reference

Fig.1

2. Fill the glass jar with distilled water until it is about 75% full

3. Pour detergent into the distilled water

4. Use the glass stirring rod to stir the mixture until the detergent and the

water have mixed, i.e. there should not be any “globs” of detergent in the

solution

5. Put all three tubes into the glass jar, and then proceed the fill the glass jar

with distilled water until the tubes are submerged, screw the top back

onto the jar

6. Leave the tubes in the detergent solution for two hours

30 2015. . [ONLINE] Available at:http://www.epa.gov/oppad001/pdf_files/test_meth_residual_surfaces.pdf. [Accessed 25 June 2015]

The marked lines5cm

18

7. After two hours take the three tubes out of the solution and thoroughly

wash under a running tap until all residue of the detergent solution has

been washed off

NB- the tubes do not need to be dried

8. Put the tubing in a clean 250ml beaker with the bottom of the tubes

touching the bottom of the beaker as shown in fig.2

Fig.2

9. Fill the beaker with 160ml 70% alcohol

10. Label this beaker “Alcohol”

11. Leave the tubing in the alcohol for 10 minutes

12. After 10 minutes, put each individual tube in a retort stand with the

bottom of the tubing facing down, and as shown in fig.3

Fig.3

Note the position of the marked lines

The bottom of the tubes touching the bottom of the beaker

19

13. Move the retort stand so that the tubes are overhanging a sink or basin as

shown in fig.4

NB- At this stage the 250ml beaker labeled with “Alcohol” should be put

aside and covered with Cling Wrap, or a paper towel to prevent the

alcohol from evaporating

Fig.4

14. Let the tubes dry for 10min

Carrying out the experiment

15. Put on gloves and safety glasses

16. Fill a 6ml glass pipet with 5ml of the E-Coli broth

17. Release the 5ml of E-Coli broth into a 500ml beaker

18. Fill the 1L beaker until the it is 500ml full with distilled water by tilting

the beaker on its side and then pouring the water down its side as shown

in fig.5

Fig.5

The marked line should be “hanging” downward

20

19. When the beaker is about 450ml full use a squirt bottle filled with

distilled water to gradually fill the beaker up to the 500ml mark, this is

your bacterial solution

20. Light a Bunsen burner and flame an inoculating loop as shown in fig.6

NB- the inoculating loop should be held above the tip of the blue flame as

this is where it is the hottest

Fig.6

21. Wait about 30sec for the inoculating loop to cool down before using it to

stir the bacterial solution to ensure that the bacterial broth is mixed with

the distilled water

22. After you have stirred the solution, flame the inoculating loop once again

to sterilize it

23. Gently pour 150ml of the bacterial solution into three beakers, after this

you should have 50ml of the solution left in the 1L beaker

24. Cover the 4 beakers with cling wrap to prevent contamination and set

them aside

21

25. Get 5 agar plates

26. Divide the first three agar plates into 3 equal sections

27. Label the three sections in each agar plate “5min”, “10min” and “20min”,

as shown in fig.7

Fig.7

28. Near the edge of the three plates, label them as which test they are, the

surface from which swabs are taken from and the dilution factor, i.e. For

the FIRST test you would label the plates, “Test 1 Dilution factor 10-2”, and

then label the plates “Copper”, “Steel” and “PVC”, an example can be seen

in fig.8, these are your “Agar plates to test surfaces”

Fig.8

29. Label one other plate “Control test: Swab only” and another plate “Control

test: Bacterial solution only”

30. Select a random swab from the pack of 100 swabs and streak the agar

plate labeled “Control test: Swab only” in a “zigzag” pattern as shown in

fig.9

Fig.9

22

31. Seal this agar plate with sticky tape

32. Get the 1L beaker with the remaining 50ml bacterial solution in it, remove

the cling wrap and pour about 10 drops into the agar plate labeled

“Control test: Bacterial solution only”

33. Close the plate and “swish” the bacterial solution around in the agar plate

by moving the plate in a figure eight pattern.

34. Seal this agar plate with stick tape

35. The 1L beaker should be disposed by giving it to a teacher or supervisor

for sterilization

36. Set up the three 250ml beakers with the bacterial solution and the three

retort stands with the clean tubing as shown in fig.10

Fig.10

37. Lower the tubing into the bacterial solutions so that the bottom of the

tubes sit on the bottom of the beakers as shown in fig.11, leave the tubes

in the solution for 10 min

Fig.11

23

38. After 10 min raise the tubes above the beakers as shown in fig.12, start

the stopwatch

Fig.12

39. When the stopwatch has reached 5 min, i.e. the tubes have dried for 5

minutes, take swabs of the three surfaces and streak the respective agar

plates in the 5 min section, i.e. a swab taken from the copper surface

should be streaked on the 5 min section in the agar plate labeled

“Copper”, swabs should also be streaked in a zigzag pattern, as shown in

fig.13 (next page)

NB- Swabs should be taken from an area below the marked line

- Used swabs should be put into a clean beaker for disposal once the

experiment is completed

Fig.13

24

40. When the stop watch has reached 10 min, take a swab of all three surfaces

again and streak the swabs in the “10min” section on the respective agar

plates

41. When the stopwatch has reached 20min, take a swab of all three surfaces

and streak the swabs in the “20min” section on the respective agar plates.

42. Seal all three agar plates with sticky tape

43. Put the 5 agar plates into an incubating oven

44. Detach the three tubes and put them in the beaker labeled alcohol to

sterilize them

45. Repeat steps 11-44, however the “Agar plates to test surfaces”, should be

labeled “Test 2 Dilution factor 10-2”

46. Repeat steps 11-44, however the “Agar plates to test surfaces”, should be

labeled “Test 3 Dilution factor 10-2”

47. Repeat steps 11-46 with a dilution factor of 10-3, i.e. only 0.5ml of the E-

Coli broth should be put into the bacterial solution

Risk Assessment:

Risk Risk reduction Accident responseE-Coli bacteria can be easily

spread if contact with it

occurs, this will cause

health issues and is a major

problem is it is wide spread

All surfaces and objects

should be sterilised before

and after use. Personal

protective equipment

(PPE) such as latex gloves

should be used throughout

the whole experiment.

Isolate affected areas as

well as people. A

professional biohazard

clean-up organisation

should be contacted to

safely clean contaminated

surfaces and to help treat

25

affected people.

E-Coli can grow to

hazardous levels once

incubated, if spores have

formed, opening the agar

plate it is inoculated on

may result in E-Coli

bacteria becoming air born.

Once incubated, agar plates

inoculated with E-Coli

bacteria should not be

opened.

Immediately isolate the

affected area and turn off

systems such as air-

conditioning, which may

disturb the air. A

professional biohazard

clean-up organisation

should be contacted to

safely clean contaminated

surfaces and to help treat

affected people.

Results:For dilution factor 10-2, refer to appendix for pictures of tests

Test #1 Dilution factor: 10-2

Time after tubing has been lifted out of bacterial solution (min)

Copper (CFU)

Stainless Steel (CFU)

PVC (CFU)

5 N/A 31 1110 N/A 26 920 N/A 21 8


Time after tubing has been lifted Copper Stainless Steel PVC (CFU)

26

out of bacterial solution (min) (CFU) (CFU)5 60 176 78

10 41 152 7020 1 126 58



Copper (CFU)


PVC (CFU)

5 71 98 7210 19 16 6620 1 81 59



Copper (CFU)


PVC (CFU)

5 0 0 010 0 0 020 0 0 0



Copper (CFU)


PVC (CFU)

5 0 0 010 0 0 020 0 0 0



Copper (CFU)


PVC (CFU)

5 0 0 010 0 0 020 0 0 0

Calculations:

CFU/ml=

Test #1- Stainless Steel- Dilution factor 10-2- 5 minute

CFU/ml=


CFU/ml=

27


CFU/ml=

Test #1- PVC- Dilution factor 10-2- 5 minute

CFU/ml=


CFU/ml=


CFU/ml=

Test#2- Copper- Dilution factor 10-2- 5 minute

CFU/ml=


CFU/ml=


CFU/ml=

Test#2- Stainless Steel- Dilution factor 10-2- 5 minute

CFU/ml=


CFU/ml=


CFU/ml=

Test#2- PVC- Dilution factor 10-2- 5 minute

28

CFU/ml=


CFU/ml=


CFU/ml=


CFU/ml=


CFU/ml=Test#3- Copper- Dilution factor 10-2- 20 minute

CFU/ml=


CFU/ml=


CFU/ml=


CFU/ml=


CFU/ml=


CFU/ml=


CFU/ml=

29

Analysis:Outliers (anomalies) are not included in average CFU/ml calculations.

Surface: Copper Dilution factor: 10-2


Test #1 (CFU/ml)

Test#2 (CFU/ml)

Test#3 (CFU/ml)

Average CFU/ml

5 N/A 6000 7100 710010 N/A 4100 1900 300020 N/A 100 100 100

Surface: Stainless steel Dilution factor: 10-2


Test #1 (CFU/ml)

Test#2 (CFU/ml)

Test#3 (CFU/ml)

Average CFU/ml

5 3100 17600 9800 1016710 2600 15200 1600 890020 2100 12600 8100 7600

Surface: PVC Dilution factor: 10-2


Test #1 (CFU/ml)

Test#2 (CFU/ml)

Test#3 (CFU/ml)

Average CFU/ml

5 1100 7800 7200 536710 900 7000 6600 483420 800 5800 5900 4167

No bacteria grew on the agar plates when the dilution factor of the bacterial

solution was 10-3. This result will be discussed in the discussion section.

30

Test # 1 Test # 2 Test # 30

1000

2000

3000

4000

5000

6000

7000

8000

9000

PVC Surface

5 minutes10 minutes20 minutes

Am

oun

t of

via

ble

bac

teri

a on

su

r-fa

ces

(CFU

/ml)

5 10 200

2000

4000

6000

8000

10000

12000

Average CFU/ml on Surfaces after tubes have been unsubmerged

Stainless SteelPVCCopper

Time after tubing has been raised out of bacterial solution (minutes)

Am

oun

t of

via

ble

bac

teir

a on

su

rfac

es

(CFU

/ml)

Test #1 Test #2 Test #30

1000

2000

3000

4000

5000

6000

7000

8000

Copper surface

5 minutes10 minutes 20 minutes

Am

oun

t of

via

ble

bac

teri

a on

su

r-fa

ces

(CFU

/ml)

31

25%

75%

Surface: Stainless SteelAmount of Viable Vacteria Killed from 5-minute Mark to

the 20-minute Mark

% of Bacteria Killed% of Viable Bacteria still remaning

23%

77%

Surface: PVCAmount of Viable Vacteria Killed from 5-minute Mark to

the 20-minute Mark


98%

2%

Surface: CopperAmount of Viable Bacteria Killed from 5-minute Mark to

the 20-minute Mark


32

Discussion

Trend in results

The second and third tests when the dilution factor was 10 -2 were carried out a

day after the first test was conducted. The results show that the first test had a

considerably lower CFU/ml with an average of 1766, when compared to the

second and third tests, which had averages of 8466 and 5838 respectively. The

most likely reason for this result is that when the bacterial solutions were left

overnight, the bacteria had a chance to reproduce. This would have increased

bacterial concentration of the bacterial solutions, i.e. there are greater numbers

of E-Coli in the solutions. As the amount of bacteria in the second and third test

killed by the surfaces would most likely remain the same as the first test, the

reason that a substantial increase in the number of viable bacteria on the three

surfaces has occurred, can be linked with higher amounts of bacteria in the

bacterial solutions when the tests were taken.

During the second test for Stainless Steel when the dilution factor was 10-2, an

abnormally large amount of water residue was observed on surface when

compared to all other tests conducted at that time. The results show that when

the agar plates were cultured this particular test had a significantly increased

CFU/ml count. As bacteria are so small, the water residue can contain millions of

bacteria cells. The main reason as to why there was an increased CFU/ml count

in this test was that the increased water residue suspended the E-Coli bacteria in

33

an aqueous solution, which not only provided a moist environment, which

encourages bacterial growth, but also prevented a vast majority of the bacteria

from coming into contact with copper surface. Referring to the background

information, in general, bacteria that are not in contact with the copper surface

are not killed.

When the dilution factor was 10-2, in all three tests for the Stainless Steel and PVC

surfaces the amount of viable bacteria present, declined at a slower rate when

compared to the copper surface. For the Stainless Steel surface and the PVC

surface, the amount of viable bacteria declined by an average of 2567 and 3600

from the 5-minute mark to the 20-minute mark. In comparison, the amount of

viable bacteria on the copper surface declined by an average of 6450 from the, 5-

minute mark to the 20-minute mark, which is more than a 160% increase than

its closest competitor which was the PVC surface. Furthermore, the percentage

decrease of viable bacteria taken from the 5-minute mark and compared with the

20-minute for the Stainless Steel and PVC surfaces was only 25.25% (4sig.fig.)

and 22.36% (4sig.fig.). However, the copper surface had a percentage decrease of

98.47% (4sig.fig). The decrease in viable bacteria on all three surfaces would

have been caused by factors such as the surface drying out. However, the

significant percentage decrease on the copper surface, would not have only been

caused by the surface drying out, as if it was the case then either the other two

surfaces would have had a percentage decrease similar to that of the copper

surface, or the copper surface would have had a percentage decrease similar to

that of the other two surfaces. From this result it can be concluded that there is

another factor involved in the killing of bacteria on the copper surface.

The tests conducted when the dilution factor was 10-3, did not show any bacterial

growth. While this result is undesirable it shows that the less bacteria there is in

an area, the lower the survival rates of the bacteria. This concept in addition with

copper’s ability to limit and reduce bacterial growth provides firm grounding for

its applications in clinical health care environments.

34

From the results and the background information (refer to “Actual studies

conducted”), this experiment has shown that copper can reduce the risk of

acquiring health related infections. The process by which copper does this can be

shown as follows:

Copper kills bacteria Bacterial growth is not only limited, but reduced

Lower numbers of bacteria present in an area mean that there is less of a chance

of bacteria surviving and remaining on surfaces in that area Less bacteria on

surfaces in an area results in a lowered risk of acquiring infections

Sources of error

After the agar plates were cured, some plates had some mould growth. This

means that either the plates were contaminated during the preparation process

of the agar plates or that the plates were contaminated during the inoculation

process when the agar plates were being streaked with the swabs. The chance of

contamination in the inoculating process could be reduced by working under a

laminar flow. Tests where the dilution factor was 10-2 were not conducted under

a laminar flow due to lack of knowledge. However, after further research

regarding aseptic technique, tests run where the dilution factor was 10-3

incorporated this technique. Evidence for working under a lamina flow actually

reducing contamination can be seen in these two agar plates.

An agar plate not inoculated under a lamina flow An agar plate inoculated under a lamina flow

35

The bacterial colonies growing in the agar plate what was not inoculated under a

lamina flow can be identified as E-Coli colonies by comparing them to one of the

controls, which was conducted by directly pouring the bacterial solution onto an

agar plate. The colonies in the control are similar to the colonies growing in the

example on the previous page in terms of shape and colour, which for this

project is enough to say that those colonies in the agar plate not inoculated

under a lamina flow are indeed E-Coli colonies

A control inoculated with the E-Coli bacterial solution only

The reason why working a laminar flow would reduce the risk of contamination

is that the air around a flame rises, i.e. hot air rises. There are mould particles in

the air around us and when this experiment is conducted in such an environment

there is always the risk that some mould particles or other contaminants may

“fall” into the agar plates. By causing the air around the agar plate to rise,

contaminants are “pushed” upwards, which reduces the chance of a contaminant

falling into the agar plate.

Another mistake that could have been made is that the surfaces were not

swabbed in the same area for the same test, i.e. when the timer counts to 5

minutes a swab is taken, however when it counts to 10 minutes a swab is taken

from the other side of the tubing. This may affect results as different areas may

Mould growing on the agar plate

36

have varying amounts of moisture on them. As written in the background

knowledge section, moist areas promote more bacterial growth than dry areas.

This may account for the 3rd test for stainless steel when the dilution factor was

10-2, where the CFU/ml was significantly lower at 10 minutes than at 20minutes.

In this case there an obvious mistake has occurred, as usually, on dry surface

bacteria numbers will decline over time instead of increase. Here, a swab for the

10-minute section may have been accidentally taken from an area that dried out

in the first few minutes, but was not swabbed for the 5-minute section or the 20-

minute section.

After the agar plates had been incubated, some of the plates were completely

dried out. Such is the case with the 1st test for copper when the dilution factor

was 10-2, where due to the agar drying out, no results were able to be obtained

regarding bacterial growth save for the fact that dry conditions do not encourage

bacterial growth. A possible cause of the agar plates drying out may be due to the

layer of agar not being poured thick enough, which is a human error.

The contamination of some of the agar plates was also partly due to a scientific

error. The amount of contaminants such as mould particles in the air could not

be controlled in the environment that these tests were carried out in. However,

this error can be avoided by working in a sterile environment such as a structure

with air locks, which requires multiple sterilisation stages before entry can be

granted. This measure would not be practical for this project due to the cost

factors involved.

Some bias also occurred in the experiment. Due to a lack of materials, bacterial

solutions were used repetitively, which may have affected the amount of bacteria

present in the solutions. This would affect results as, by lowering the amount of

bacteria in a solution, the bacteria may be killed in greater numbers. Evidence for

this rational can be seen in the background research section.

Reliability, validity, and accuracy of data

37

The data in this experiment was made reliable by repeating the experiment

multiple times. All data obtained in this experiment was reliable as all except two

results followed a general trend, i.e. data for the Copper, Stainless Steel, and PVC

surface, followed individual trends for the respective surfaces. The general trend

was that as the time period, in which the surfaces were unsubmerged, increased,

the CFU/ml on the surfaces decreased. Of the two anomalies the first was that

the agar plate containing the first test for the copper surface when the dilution

factor was 10-2 had completely dried up in the incubating oven. However, just

because no bacterial growth could be observed, it does not show that there was

no bacterial growth at all. Perhaps there was some bacterial growth but it

disappeared after the agar dried out. The second anomaly was the swab taken at

the 10-minute mark for the third test of Stainless Steel when the dilution factor

was 10-2.

The validity of the data collected in this experiment was affected by one main

factor, the repeated use of bacterial solutions. Due to a lack of materials a

bacterial solution could not be made for each individual test. As a result the same

bacterial solution had to be used for three tests, i.e. the bacterial solution with a

dilution factor of 10-2 was used for three tests before being disposed of. After the

initial use of the bacterial solutions, there may be different amounts of bacteria

in the solutions themselves. This would decrease the validity of the experiment

as during the second and third use of the bacterial solutions, different amounts of

bacteria would be being put onto the surfaces. A possible reason as why there

would be different amounts of bacteria in the solutions would be that, for

example in the case of copper it may kill more bacteria while it is submerged in

the E-Coli solution than the Stainless Steel surface or the PVC surface.

As there are no set results (“real results”, an example being Acceleration due to

gravity), to compare this experiment with, it would not be appropriate to

comment on the accuracy of the data collected.

Future Studies

38

This experiment could be further extended by testing a wider range of bacteria in

a wider range of dilutions, i.e. 10-1, 10-1.2, 10-1.4, 10-1.6, 10-1.8, 10-2, 10-2.2. With the

different types of bacteria, antibiotic resistant bacteria such as MRSA could be

tested to see if the effect of copper was different between antibiotic resistant

bacteria and non-antibiotic resistant bacteria. Copper alloys with different

percentages of copper could also be tested to see which percentage of copper

was most effective in limiting bacterial growth and was most cost effective.

Conclusion:

From these results and the discussion a conclusion can be reached, which is that,

copper can be used as an antimicrobial agent to limit bacterial growth. These

results also show that copper has practical applications in clinical healthcare

environments such as hospitals, as by lowering the amount of bacteria present,

you lower the risk of infections.s

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Appendix:

Glossary of terms

Convection current- a current in which warm air rising and cooler falling

Bactericide- substance that kills bacteria

Phospholipid- a class of lipids that are a major component of all cell membranes

Solutes- substance dissolved in another substance known as a solvent

Extrachromosomal DNA- DNA found outside of the nucleus that are not required

to perform day to day functions but have important biological functions

Subunit- A subdivision of a larger unit

Haber-Weiss and Fenton reaction- A reaction in which hydroxyl radicals are

produced

Macromolecules- Very large molecules commonly created by the merging of

smaller subunits

Lipid peroxidation- A process in which free radicals cause cell damage, resulting

in the oxidative degradation of lipids

Metalloproteins- A protein that contains metal ions as a cofactor

HCAI- Health Care Associated Infections

Desiccating- the removal of moisture from something

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· web viewantibiotic resistant bacteria are a prominent issue in modern day society and are...

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