Non-invasive diagnostic test developed for strep throat

Streptococcus pyogenes, commonly known as ‘strep throat’, is a common bacterial infection that causes a sore throat. In most cases, no treatment is needed and the infection resolves itself. Serious complications can, however, follow, for instance the development of rheumatic fever.

Such complications are particularly common in children and elderly patients, and as such, a quick and accurate diagnostic test for this condition is of great importance, allowing rapid prescription of antibiotics.

Currently, strep throat is diagnosed using the ‘Rapid Antigen Detection Test’, providing results within 15–20 minutes. Disadvantages of this test are that it can provide false positives, and also that it requires a trained individual to administer.

Alan Jarmusch and colleagues (Purdue University, IN, USA) collaborated with researchers at the University of Turin (Italy) on this project to develop a novel test for strep throat diagnosis. The test provides results within a few seconds, offering advantages over the currently used technique.

First, a swab is taken from the patient’s throat. Voltage is then applied to the swab to create ions. If S. pyogenes is present in the sample, these ions are derived from (and therefore specific to) the bacteria. The resultant ions are then passed through a touch spray MS system, with pattern recognition software being used to detect ions. If S. pyogenes is present, then ions specific to this bacteria will be detected and a positive result generated.

Looking to the future, the team plan to expand their research to study other bacteria, with implications for diagnostic tests in a variety of diseases.

Source: Jarmusch JK, Pirro V, Kerian KS, Cooks RG. Detection of strep throat causing bacterium directly from medical swabs by touch spray-mass spectrometry. Analyst DOI: 10.1039/C4AN00959B (2014) (Epub ahead of print).