New defences against necrotising fasciitis
Don't panic: severe soft tissue infections are extremely rare. But if you do develop one, you and your doctor need to act quickly. An EU-funded project is working on a powerful diagnostic tool that can help to spot these potentially fatal illnesses early. The team is also analysing patient records and samples from several countries to identify the best treatments.
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The Infect project studies severe soft tissue infections, such as necrotising fasciitis, to shed new light on the factors that cause them. Building on this information, the partners intend to develop tests that will permit doctors to detect these infections more rapidly and take immediate action to save the patient’s life and limbs.
Forget flesh-eating bacteria
Contrary to a widespread misconception, necrotising soft tissue infections (NSTIs) aren’t caused by some rare pathogen few of us are likely to encounter. They can be triggered by very common bacteria, which may be living on our skin or in our throat. Nor do they “eat” the flesh, as such, although it is indeed destroyed: tissues die off as the infection spreads.
Very minor injuries — a paper cut, or even a bruise — can enable the bacteria to make their way into the flesh. What happens next depends both on the host and on the pathogen. Infection, if it does develop, may be mild. Then again, it could be disastrous.
“We know that severity is determined by the combination of a particular bacterium and a particular patient,” says project coordinator Anna Norrby-Teglund of Karolinska Institutet in Stockholm, Sweden. “Your genetic make-up, your immune response, whether or not you have been exposed to the bacteria before, all of this will influence how susceptible you are to that particular strain,” she notes.
This is a general explanation, but there is still a lot to learn, Norrby-Teglund explains. Infect intends to generate new knowledge. Information and biological material from patients identified by doctors involved in the project are enabling the team to study how the disease evolved in a large number of cases, in a bid to identify key specificities of pathogens and patients.
“Our doctors have set up a clinical database covering more than 280 cases, and we have assembled more than 6 000 biobank samples,” says Norrby-Teglund. “This will enable us to identify the bad matches that lead to severe disease.”
In order to facilitate studies in the lab, the team has found a way to grow human tissue from skin cells. “This enables us to follow the onset and the progression of the infection in the tissue in more detail and will help us to delineate the underlying mechanisms,” says project manager Mattias Svensson, also of Karolinska Institutet.
No time to waste
NSTIs are aggressive infections that rampage under the skin, gaining ground with every minute. They are very dangerous, with mortality rates that often exceed 30%, and can leave survivors disabled. And yet, in the initial stages, there may not be much to see. Patients feel extremely unwell, but none of the symptoms are necessarily a clear indicator of the ongoing tissue destruction.
“That’s the problem. When the patients come in, it can be hard to diagnose them as some only have vague flu-like symptoms. Many have a disproportionate severe pain without any visible signs of grave damage,” says Norrby-Teglund. Other than that, doctors may not have a lot to go on.
And yet, urgent treatment is needed to tackle an NSTI. Usually, it involves immediate antibiotic treatment and surgery to remove the infected flesh.
Infect is developing diagnostic tests that can help hospitals to identify NSTIs much earlier than current approaches, pre-empting any delays to prompt treatment. These kits, which will test for all the various patient and pathogen specificities that Infect identifies as particular risk factors, will enable doctors to assess samples within 30 minutes, Norrby-Teglund notes.
With the current progress of the Infect project these powerful diagnostic tools are likely to be available by the time the project ends in December 2017. In addition, the partners intend to identify the most effective treatments and provide evidence-based guidelines.
Greater awareness could also help to reduce the death toll, and Infect is doing its bit to spread the word. NSTIs may be rare, but they do exist, and patients and medical staff need to know more about them, Norrby-Teglund concludes.