March 2010 - Swinburne University of Technology
March 2010 - Swinburne University of Technology
March 2010 - Swinburne University of Technology
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march <strong>2010</strong> swinburne<br />
‘Clingy’ bacteria surprise<br />
comes to the surface<br />
story by Diny Slamet<br />
Improving the success rate <strong>of</strong> artificial<br />
implants. Reducing the risk <strong>of</strong> dangerous<br />
Staphylococcus outbreaks in hospitals.<br />
Dramatically reducing the amount <strong>of</strong> fuel<br />
oil burned by the world’s merchant shipping<br />
fleet. It is a disparate list, but nonetheless it<br />
is the set <strong>of</strong> research goals that a <strong>Swinburne</strong><br />
<strong>University</strong> <strong>of</strong> <strong>Technology</strong> research team has<br />
begun to pursue.<br />
The issues all stem from bacterial activity,<br />
in particular the way bacteria adhere to<br />
surfaces by creating a ‘bi<strong>of</strong>ilm’ that protects<br />
the bacteria from the usual sterilisation<br />
treatments.<br />
The <strong>Swinburne</strong> team, working with<br />
specialists from Monash <strong>University</strong>,<br />
combines the skills <strong>of</strong> scientists <strong>of</strong><br />
different specialisations – microbiology,<br />
nanotechnology, engineering and industrial<br />
sciences – to seek remedies that cannot be<br />
achieved by one discipline alone.<br />
The team is led by microbiologist<br />
Pr<strong>of</strong>essor Elena Ivanova and includes<br />
surface chemist Pr<strong>of</strong>essor Russell Crawford<br />
– who is also Dean <strong>of</strong> <strong>Swinburne</strong>’s<br />
Faculty <strong>of</strong> Life and Social Sciences – and<br />
physical metallurgists Pr<strong>of</strong>essor Yuri Estrin<br />
and Dr Rimma Lapavok from Monash<br />
<strong>University</strong>.<br />
The problems caused by bacteria cost<br />
industries such as healthcare, hospitality<br />
and shipping billions <strong>of</strong> dollars each year.<br />
The rewards to individuals and society for<br />
solving the more intractable problems, such<br />
as hospital-borne infections, are immense.<br />
One <strong>of</strong> the most troublesome issues <strong>of</strong><br />
modern medicine is infection-related implant<br />
failures. According to Pr<strong>of</strong>essor Ivanova,<br />
up to 67 per cent <strong>of</strong> implants are troubled<br />
by bacterial problems. Despite thorough<br />
sterilisation processes, this high percentage <strong>of</strong><br />
medical implants (commonly hips and knees)<br />
fail because some types <strong>of</strong> bacteria attach to<br />
the implant as a bi<strong>of</strong>ilm, from which they<br />
cause further infection. The only solution is<br />
to remove the infected implant and replace it.<br />
The research team has already made great<br />
strides by disproving a common hypothesis<br />
that had previously led researchers down a<br />
blind alley. While not a great deal is known<br />
about the forces that attract bacteria to<br />
solid surfaces, the common hypothesis was<br />
that bacteria attach more easily to rougher<br />
surfaces because the microscopic valleys on<br />
that surface provide shelter from commonly<br />
used disinfection processes. Some implant<br />
manufacturers are even going down the road<br />
<strong>of</strong> making their products ‘nano-smooth’ so<br />
the bacteria cannot find protection from<br />
sterilisation processes.<br />
But the scientists have made a surprising<br />
discovery. Working with nano-smooth<br />
titanium and a range <strong>of</strong> microbiological<br />
analysis techniques, the researchers have<br />
found that rather than making it harder for<br />
bacteria to adhere to, smooth surfaces seem<br />
to be more attractive to some problematic<br />
bacteria, with a higher degree <strong>of</strong> bacterial<br />
colonisation on smooth surfaces than on<br />
rough.<br />
“The way bacteria attach to nanosmooth<br />
surfaces is different to the way<br />
they adhere to rough surfaces,” explains<br />
Pr<strong>of</strong>essor Crawford. “The bacteria adhere to<br />
these surfaces by secreting an extracellular<br />
polymeric substance (EPS), which is a<br />
combination <strong>of</strong> sugars and proteins. This<br />
is the first time it has been shown that the<br />
EPS is produced in much greater quantities<br />
when bacteria come into contact with nanosmooth<br />
surfaces, causing a greater amount <strong>of</strong><br />
bacterial attachment.”<br />
The research suggests that hospitals may<br />
have to rethink their disinfection techniques<br />
and that manufacturers may have to develop<br />
new disinfectants.<br />
“Many bacterial disinfectants used today<br />
are based on positively charged (or cationic)<br />
surfactants. These attach to the negatively<br />
charged bacteria, causing their cell wall<br />
to rupture and killing the bacteria. This<br />
new research has highlighted the need for<br />
disinfectant manufacturers to formulate new<br />
products that attack both the EPS and the<br />
bacterial cells, and not just the bacterial cells<br />
alone,” Pr<strong>of</strong>essor Crawford says.<br />
Shipping is another industry where the<br />
<strong>Swinburne</strong> research may contribute to a big<br />
increase in efficiency. Scientists estimate that<br />
a bi<strong>of</strong>ilm (or bacterial build-up) the thickness<br />
<strong>of</strong> just a human hair on a ship’s hull can<br />
add US$400 an hour to fuel costs because it<br />
affects the ship’s drag, causing greater fuel<br />
consumption.<br />
Most <strong>of</strong> the techniques used to limit the<br />
build-up <strong>of</strong> bi<strong>of</strong>ilm on ships’ hulls work for<br />
Photo: iStockphoto / Malcolm Fife<br />
<strong>Swinburne</strong> research will help to develop surface<br />
coatings that reduce the ability <strong>of</strong> bacteria to<br />
build a film on ships’ hulls. This could save<br />
the global shipping industry millions <strong>of</strong> tonnes<br />
<strong>of</strong> oil a year because the ships will be able to<br />
move through the water more easily.<br />
a limited time and have a severe ecological<br />
downside, with toxic chemicals being used<br />
in most marine paints.<br />
The <strong>Swinburne</strong> research is adding to<br />
the body <strong>of</strong> knowledge that will lead to the<br />
development <strong>of</strong> surface coatings that can<br />
reduce the ability <strong>of</strong> bacteria to build a film<br />
on ships’ hulls. This could save the global<br />
shipping industry millions <strong>of</strong> tonnes <strong>of</strong> oil a<br />
year because the ships will be able to move<br />
through the water more easily.<br />
The work <strong>of</strong> the <strong>Swinburne</strong> scientists<br />
is still at the early research stage. “We are<br />
really looking at what causes bi<strong>of</strong>ilms to<br />
form and how well they form on a range<br />
<strong>of</strong> different surfaces. Once we publish<br />
our results we hope they will be used<br />
by companies to produce more effective<br />
disinfection processes and surface coatings,”<br />
Pr<strong>of</strong>essor Crawford says. ••<br />
Contact. .<br />
<strong>Swinburne</strong> <strong>University</strong> <strong>of</strong> <strong>Technology</strong><br />
1300 275 788<br />
magazine@swinburne.edu.au<br />
www.swinburne.edu.au/magazine<br />
Key points<br />
The way bacteria adhere<br />
to surfaces – by creating a<br />
‘bi<strong>of</strong>ilm’ that protects them<br />
from the usual sterilisation<br />
treatments – is being<br />
investigated<br />
The <strong>Swinburne</strong> research<br />
team, working with<br />
specialists from Monash<br />
<strong>University</strong>, combines<br />
skills in microbiology,<br />
nanotechnology,<br />
engineering and industrial<br />
sciences<br />
The work could improve<br />
the success rate <strong>of</strong> artificial<br />
implants, reduce the risk <strong>of</strong><br />
Staphylococcus outbreaks<br />
in hospitals and reduce the<br />
fuel consumption <strong>of</strong> ships<br />
surface science<br />
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