Criteria and characteristics of Syndromic testing

What is syndromic testing?

Syndromic testing is the process of using one test to simultaneously target multiple microorganisms with overlapping signs and symptoms.

Multiplex molecular panels can detect a range of microbiological targets (e.g. different species of bacteria, viruses or fungi) that are associated with a particular clinical syndrome, for example, meningitis or respiratory disease.

How does it work?

A patient sample (e.g. CSF sample in the case of suspicion of meningitis) is pipetted into a cartridge or pouch containing all the necessary reagents for RNA/DNA extraction, amplification, and detection of an extensive range of microorganisms related to a specific syndrome.

Nucleic acids

Firstly, nucleic acids of the microorganisms present are purified from the patient sample. If necessary, viral RNA is converted to DNA via reverse transcription.

The nucleic acid is then amplified during the PCR reaction using primers. Multiplex PCR, where numerous primers are present, amplifies the nucleic acid of multiple targets in a single chemical reaction.

Amplification

Amplification may be in a single step or in two steps using nested PCR. Specific amplification products can then be detected via different methods (e.g. using a fluorophore).

The entire process will be automated and take place inside the pouch or cartridge. Interpretation and reporting of results are conducted using test-specific software.

The diagram below shows a schematic of the steps to detecting and identifying microbes using syndromic testing:

If you require a text version of the above image, this is available as a PDF.

To take a closer look at the schematic, click here

When it should be used

The early identification of causative microorganism(s) in patients with severe infection is crucial in optimising antimicrobial use and patient outcome.

The slow turnaround time for results from conventional methods frequently results in the empiric use of broad-spectrum agents, with potential side effects to the patients and long-term consequences for antimicrobial resistance.

Fast identification of pathogens and antimicrobial resistance genes can promote antimicrobial stewardship and facilitate more informed patient management decisions.

However, there are clinical situations where other diagnostic methods would be preferred.

For example, a patient presenting at a GP with flu symptoms is less likely to benefit from a syndromic test, compared to a critically ill patient requiring urgent care.

If you’d like to learn more about syndromic testing, check out the full online course, from BASC, below.