In the face of growing crises related to antibiotic resistance and hospital–acquired infections, a UW–Madison spinoff called Isomark is working to introduce a new infection–detection technology into hospital intensive care units.

Isomark’s system measures carbon isotopes in exhaled breath. Without even touching the patient, it can offer the earliest warning of severe bacterial infection, says founder Mark Cook, a professor of animal science at the University of Wisconsin–Madison.

In 2005, Cook, Warren Porter, a professor of zoology, nutritionist Dan Butz, and others formed Isomark to pursue their “hands–off” detection invention.

Isomark’s system can often spot a bacterial infection before the patient feels symptoms, raising the potential for faster, better treatment for severe infections. The company is focused on ICUs, which treat about 5 million people in the United States each year, and where sedation or breathing tubes can block communication about symptoms.

When the immune system responds to an infection, subtle changes in the ratio of the common carbon 12 isotope and the rare carbon 13 can be detected long before a doctor, blood test, or often even the patient, knows that an infection is present. (Isotopes are chemically identical versions of an element that can be distinguished from their differing masses.)

After gathering breath samples and medical records from 100 ICU patients, Isomark saw a telltale change in the isotope ratio for each patient who became ill. “Our studies show that we are 18 to 48 hours ahead of when clinicians suspect an infection,” Cook says.

Since the test measures non–radioactive isotopes in exhaled breath, the procedure is non–invasive and safe.

The testing process could hardly be simpler. The patient breathes into a bag (or a sample is grabbed from a ventilator). The bag is connected to the tester, the patient ID is punched in and results appear in 10 minutes.

The testing technology relies on principles discovered during the 1960s by W. Wallace Cleland, an enzyme scientist at UW–Madison, says Cook. “During an infection, immune cells produce cytokines that rev up the immune system, causing the release of amino acids to support the immune reaction. The amino acids are burned for energy through a long chain of enzyme reactions that ‘discriminates against’ carbon 13, Cook says, changing the carbon 12/carbon 13 ratio in exhalations.

The change is only a few parts per million – but enough to be measured in a spectrograph. Until recently, the necessary instrument cost nearly $500,000; newer models are coming in at about $100,000, Kremer says. The lower price is key to the growing commercial potential of the procedure.