From causing high temperatures to full-on shock, sepsis is one of the nastiest diseases around. But diagnosing the illness is frustratingly hard. Though doctors have more than 100 drugs to treat sepsis-causing pathogens, the disease can be caused by a range of fungi and bacteria. This makes proper treatment difficult, a situation that is not helped by inaccurate blood culture tests. But by using a new generation of assays, doctors have a chance to finally diagnose sepsis quickly and efficiently, saving lives and money along the way.
Dr Thomas Walsh is all too aware of these problems. As the founding director of the transplantation, oncology and infectious diseases programme at Weill Cornell Medicine, and New York-Presbyterian Hospital, he has worked hard to find faster and more accurate ways of diagnosing sepsis. "Within our research, we have a long-standing threedecade heritage of working in the field of rapid molecular diagnostics," Walsh explains. "The rapid diagnostics are particularly valuable for Candida [fungus, which is work] that we've been pursuing since the mid-1980s."
Though blood culture tests are getting better, they are still "quite deficient", Walsh says. "They are not able to recognise Candida within 19-24 hours [of a test] and are perhaps not able to recognise a species until maybe 48 hours after the initial draw." Other tests for bacteria have similar problems, Walsh continues. "We miss cases," he acknowledges.
These lacklustre tests make sepsis incredibly pricey to treat. It was the most expensive condition treated in US hospital stays in 2016, costing about $27 billion for nearly 1.6 million hospitalisations. The human consequences are just as enormous. Candida - one of the fungal causes of sepsis - has a shocking 40% mortality rate. Apart from taking a dangerously long time to get results, blood culture tests can also miss sepsis-causing pathogens 50% of the time.
Fortunately, not all diagnostic tests are so unreliable. By developing a range of products that test patients directly from whole blood, rather than relying on blood cultures, T2 Biosystems circumvents many of the downsides of traditional sepsis assays. For its part, T2's Candida test, termed the T2Candida Panel, is 91.1% sensitive and can yield results in as little as three hours from blood draw. Walsh has already seen the benefits of this test on the patient wards.
"Our assessment is still ongoing, but we believe that [T2Candida] can be an important adjunct in the management of our critically ill patients," Walsh explains. It helps that doctors can be confident that results from T2's system are accurate, he adds. "We believe it has a sufficiently high negative predictive value to allow us to discontinue therapy after a certain assessment."
The consequences of better testing could be huge, Walsh suggests. "Early detection and early therapeutic initiation for candidemia clearly saves lives. In that regard, the impact for society, above and beyond the hospital is striking." Keeping sepsis at bay could also save his team money. "If we can reduce length of stay from the complications of untreated candidemia, that can also significantly reduce hospitalisation and length of stay, and thereby [reduce costs] to the hospital," he says. Other hospital systems have already realised cost savings by using the T2Candida panel. For example, Lee Health in Florida reported saving $200 for every patient tested.
Walsh came away similarly impressed with the T2Bacteria Panel, especially after working with the system during a clinical trial. "T2Bacteria was able to detect the presence of bacteria significantly earlier - certainly within approximately six hours - compared with 24 to 48 [hours, for blood culture tests]," he says. "It [can also detect] five major pathogens, including E. coli and enterococcus." Just as with T2Candida, Walsh expects T2Bacteria could transform the battle against sepsis. "We were very favourably encouraged from the results of the study and it could be an important therapeutic advance," he says.
Regardless of which test Walsh uses, they are striking in their simplicity. After all, the T2Bacteria and T2Candida Panels use the T2Dx Instrument, a fully automated platform with a user-friendly interface. It is no wonder doctors are flocking to use T2 Biosystems' tests - and finally fighting sepsis with the best tools available.