Novel Coronavirus COVID-19 testing can now occur on site at Mackay Base Hospital and our pathology team couldn’t be more excited!
The Mackay Pathology lab has received its first shipment of the brand-new SARS-CoV-2 testing cartridges.
The testing is done on the laboratory’s GeneXpert analyser and the great news is it only takes one hour to receive the result.
Due to the international demand and limited supply of GeneXpert cartridges, onsite COVID-19 testing is only available for our Aboriginal and Torres Strait Islander communities and other urgent cases at the discretion of our Infectious Diseases Physician.
At this stage, COVID-19 samples that don’t meet the onsite testing criteria will continue to be sent to Townsville or Brisbane for testing, until such time as more cartridges become available.
A sample is taken from the back of the nose and throat using a Floq swab.
The swab is taken to pathology 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.
The SARS-CoV-2 testing cartridge is then loaded into the GeneXpert analyser for processing.
So what happens inside the analyser? 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.
PCR is gold standard and extremely accurate.
The whole process, from preparation to result, take less than one hour.
Here is a great 3D animation of the process: