Issue Three 2012 - Issue #17
Story by James Hutson
Each year in Australia there are more than 5.4 million cases of gastro, involving 15,000 hospitalisations and 80 deaths. The burden on the healthcare system is over $1.2 billion per annum, with additional costs arising from loss in lifestyle and productivity.
Gastrointestinal illnesses are generally caused by three types of bacteria: E. coli, salmonella and campylobacter jejuni. The general public tends to be more familiar with salmonella outbreaks, but Louise Dunn, investigator and program manager for Swinburne’s Bachelor of Health Science degree, notes that campylobacter jejuni is the most significant cause of food-borne illness in Australia and worldwide.
“We have about 6000 cases per year being reported in Victoria. It is a significant burden. The incidence of infection also appears to be increasing across all age groups, including children and young adults.”
Difficult to detect
A big problem with identifying and controlling campylobacter jejuni is that most of the infections seem to be sporadic. It might be from contaminated water or contact with pets, birds, animals or food (such as chicken, offal or undercooked meat).
“Outbreaks aren’t always occurring in a particular pattern or interval, they are just an occurrence, and each year only one or two outbreaks are detected,” says Dunn. “This means that there is not enough information about how to manage and detect the source of the infection.”
Current testing methods are time consuming and require skilled personnel. The current “gold standard” uses gel electrophoresis to genetically differentiate the specific strain (genotyping). Growing cultures of the sample for genotyping analysis takes three to four days, a delay that makes tracing the origin of the contamination through accurate interviews and further sample collecting more difficult.
Finding the source
Tracing the origin or source of the contamination is critical if health outcomes are to improve. The Victorian Department of Health is looking for ways in which they can use evidence for better decision-making. To this end they have awarded a research scholarship to Swinburne PhD student Monir Ahmed to focus on more rapid ways to detect campylobacter jejuni and better inform the Victorian Department of Health’s policies.
“Swinburne has a long-term relationship with the Victorian Department of Health,” says Dunn. “We produce a lot of graduates who work in regulatory and surveillance areas within local and state government departments and this scholarship allows us to investigate how we can help the food safety system by developing techniques for detecting outbreaks of campylobacter jejuni more readily.”
Instead of relying on genotyping, Ahmed has obtained samples from the University of Melbourne’s Microbiological Diagnostic Unit and is working to identify a selection of virulent (toxin) genes associated with the campylobacter infection. These gene groupings could then be used to more quickly and accurately identify and categorise different strains.
Ahmed uses Swinburne’s MALDI-TOF mass spectrometer to accurately identify strain-specific metabolic fingerprints. These results are then fed into a database of different cell proteins allowing the comparison of new strains with those previously identified. In an outbreak situation this method could be used to quickly differentiate between unrelated strains and those from the same source.
“Analysis is very quick,” says Professor Elena Ivanova, microbiologist and one of Ahmed’s PhD supervisors. “You can get the preparation stage down to one day and then get the results through the MALDI-TOF in half an hour.” This greatly reduces the time and effort required to identify the origin of a campylobacter jejuni contamination, meaning that improved education, regulation or clean-up policies could be applied, therefore also addressing some of the public health costs.
Developing a field-portable biosensor to aide in tracing the source is the project’s ultimate goal. Fighting future outbreaks of gastroenteritis will draw on these technologies, ensuring better health outcomes for Victorians.