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5 June, 2020

New machine can test for COVID–19 locally in hours

A NEW METHOD of testing for coronavirus (Covid-19) at Longreach Hospital can deliver results within hours, eliminating the need for some Central West test samples to be flown to Brisbane or Townsville for analysis.


Pathology Queensland Longreach Hospital Medical Scientist Lucy Ballard drops a swab sample into a liquid medium inside a Biological Safety Cabinet to prepare it for analysis.

Deputy Premier and Minister for Health and Ambulance Services Steven Miles said this meant faster turnaround times and testing closer to home for most of our rural and regional towns and our vulnerable Aboriginal and Torres Strait Islander communities.

“Previously, all test samples would have had to be collected and sent to Brisbane or Townsville for analysis with a potential wait of 48–72 hours for results to be returned, especially given the reduction in the frequency of scheduled flights to the region,” Mr Miles said.

“Now, selected samples can instead be sent to Longreach Hospital where a new, $32,000, automated Cepheid GeneXpert testing system is housed.

“The advantage of the new GeneXpert testing system and the special SARS-CoV-2 testing cartridge it uses is that it has a fast turnaround time of within an hour, with the result then quickly available to the treating clinician.

“It also reduces the stress of waiting for results to return from outside the region.

“The GeneXpert tests are highly accurate and work by detecting the unique genetic profile of the Covid-19 virus.”

Central West Hospital and Health Service Executive Director of Medical Services Dr David Walker said the Covid-19 testing cartridges initially would be used only for vulnerable Aboriginal and Torres Strait Islander communities and other urgent cases at the discretion of infectious diseases experts, as international demand for the cartridges was so great only a limited supply currently was available.

But as access to cartridges increased, so would the number of tests that would be able to be done locally.

Dr Walker said Central West Health had trained and qualified pathology laboratory staff at Longreach Hospital able to run the GeneXpert system safely and efficiently.

“The process starts with a swab sample being taken from the back of the nose and throat of a patient,” he said.

“The swab is then sent to our pathology laboratory at Longreach Hospital to begin the testing process.

“Inside a Biological Safety Cabinet, the scientist suspends the swab sample into a liquid medium. The liquid is then loaded into a single-use-only SARS-CoV-2 testing cartridge.

“The Biological Safety Cabinet is a sterile environment, so it reduces contamination risk to the sample, and protects the scientist from aerosols/infection.

“Once the liquid medium is loaded into the SARS-CoV-2 testing cartridge, the cartridge is loaded into the GeneXpert analyser for processing.

“It’s quite amazing as an entire molecular diagnostic laboratory is packaged into this tiny cartridge.

“There are reagents and chemicals inside, and all the reactions take place inside the cartridge, through a process called PCR (polymerase chain reaction).

“Through sonic sound, the sample releases its genetic material (RNA in viruses), and then the reagents are added in.

“The reagents are specially programmed to amplify the target RNA. In this case, it amplifies the SARS-CoV-2 RNA specifically — if there is any in the sample.

“The GeneXpert analyser repeatedly heats and cools the sample and illuminates it with LED light colours to make the DNA amplification happen.

“If there is SARS-CoV-2 RNA present, the sample grows brighter, which is detected by a colour detector. This is a positive sample. If there is no colour change, it is a negative sample.

Dr Walker said the PCR test was gold standard and extremely accurate.

“The whole process, from preparation to result, takes less than one hour,” he said.

As well as COVID-19 tests, the GeneXpert system can be loaded with cartridges that can test for Influenza A, Influenza B and for Respiratory Syncytial Virus (RSV), which is at common cause of bronchitis and pneumonia in children.

RSV also can affect older people with heart, lungs or immune system problems.

“By having a diagnosis of any of these viruses within a very short time period, treatment options will be greatly improved for our patients who have the virus-related conditions,’’ Dr Walker said.

“In addition, the rapid detection of such viruses is an important factor for controlling and isolating outbreaks.

“In the future, new analysis cartridge packages being developed for the GeneXpert system also could be used to identify other viruses such as enterovirus and norovirus which can be responsible for outbreaks of sickness in our region.’’


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