Diagnostics
Vitamica is developing an antimicrobial susceptibility test that detects fluctuations in individual bacterium using a microscope.
detects fluctuations within the individual bacterium. “Using a microscope, you look at bacteria in a sample and add an antibiotic,” says Avison, who sits on Vitamica’s scientific advisory board. “This microscope shines an evanescent field onto the bacteria, and you see the bacteria shimmer and wiggle. I call it a wiggle- ometer. If the antibiotics are having an effect on the bacteria, that wiggling slows down, and if the bacteria are resistant to the antibiotic, the wiggling carries on. You see that effect within just a few minutes of the antibiotic being present.”
There are a few more speculative technologies on the horizon too, involving next-generation sequencing, metabolomics and transcriptomics. With the costs of sequencing falling every year, these kinds of approaches are starting to become more feasible. “If you know an organism’s entire genome, then in principle you can deduce whether certain resistance genes or susceptibility pathways are present,” says van Belkum. “That will give you an opportunity to do a computer search for those resistance markers, which will then tell you what sort of antimicrobials can still be used and for which ones this bug is probably resistant.”
The bigger picture Both Avison and van Belkum, while optimistic about the potential for rapid AST, see a number of obstacles to implementing them in healthcare systems. Avison points out that, while there is definitely a desire within the health service to speed up AST, it can be hard to get labs to agree on what that looks like in practice. Van Belkum adds that since the current systems are cheap, automated and high-throughput, labs need to be convinced that the newer systems are just as good. “There are these promising rapid systems that do their thing in about 20 minutes,” he
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says. “But if you want to put an instrument like that into a clinical laboratory, then it needs to be capable of what the current automated systems are capable of – which is tens of antimicrobials, multiple dilutions, for a vast array of different microbial species.” He warns too that many new technologies, such as sequencing, won’t be practicable in developing countries. AMR is a global problem, and as such, it will be important to focus on technologies that are suitable for resource-poor settings. “What is technically feasible, and what we can afford here in Western countries, is important because it sets the stage of what can be done in the end,” he says. “But AMR is not a local issue. You should always put your technologies into an international framework, where that type of technology is available to all, because otherwise, it’s not going to solve the problems that we’re facing.” Avison believes that, despite some of the challenges around implementation, we will start to see rapid AST using visualisation methods within the next five years, and genome sequencing approaches in the 2030s. “I think the next five to ten years is when we’re going to see a sea change in the way we do susceptibility testing,” he says. “At the moment, it’s pretty much the same as we would have done it 50 years ago, apart from a few more bells and whistles.” However, he remarks that the introduction of new technologies won’t automatically lead to a change in the way antibiotics are prescribed. It will fall to clinicians to use this rapid AST judiciously, with a view to making an impact on antibiotic resistance. “I think we need to perhaps do some work around encouraging practice, rather than just assuming the technology will dig us out of a hole,” he says.
Practical Patient Care /
www.practical-patient-care.com
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