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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 />

3

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