THE surgeon was poised to carry out a skin graft when he decided to try out an experimental device to check for infection. Called the MolecuLight i:X, it shows the presence of bacteria in real time as an eerie fluorescent glow.
The patient was a 47-year-old man whose leg had been amputated above the knee. He had endured one infection already and the surgeon didn’t want to risk another.
“I was ready to perform surgery on this patient. The wound looked clean,” says Steven Jeffery of the Royal Centre for Defence Medicine in Birmingham, UK. One look through the machine, however, and the operation was called off. The wound glowed red at the edge, showing it was riddled with bacteria that would probably have caused the skin graft to fail.
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When the wound was swabbed and tested in the lab it confirmed that harmful bacteria were present. The skin graft was delayed until the wound had healed, which Jeffery says led to a better outcome. Using the device “completely changed my decision-making”, he says.
Wound infections are a big problem in medicine. Swabs can be taken and sent to a lab for testing but this takes days, which can delay treatment. On the spot, doctors can only inspect the wound, touch it to see if it is too warm, or even sniff it. But they don’t want to use antibiotics unnecessarily as this can cause side effects and lead to drug resistance. And sometimes there are no early signs of infection.
Launched in October, the MolecuLight i:X is a little larger than a smartphone. It emits light at a wavelength of 405 nanometres – perfect to spot bacteria, which have molecules called porphyrins that fluoresce at this wavelength. When held over a patient’s wound, the screen shows it augmented with glowing red where there are certain bacteria, or in the case of one type, blue-green.
Apart from the blue-green species, it doesn’t distinguish between different types of bacteria, nor does it indicate their quantity.
Swabs may still need to be tested but the device shows where they should be taken, says Rosemary Hill of Lions Gate Hospital in Vancouver, who has been field-testing it. Wounds are usually swabbed from the centre but the MolecuLight i:X has been showing that bacteria may be present only around the edges.
“The presence of bacteria does not mean the existence of active infection,” says Ewen Harrison at the University of Edinburgh, who isn’t involved in the research.
Two small trials have linked the device with faster wound healing partly by showing where wounds should be swabbed, although neither were randomised.
This article appeared in print under the headline “Wound scanner picks out infection”
