Affordable portable AMR diagnostic at the point of care

Despite the progress that has been made in the last few years with molecular AMR diagnostics, most of them rely on access to large expensive laboratory equipment and reagents which tend to be the preserve of well-resourced laboratories. In addition, most outputs from molecular based tests cannot be read easily without special training. Such problems therefore render molecular tests largely inaccessible and unaffordable to low and middle income countries (LMICs) where AMR poses the greatest risk.

Another problem is that most rapid diagnostics target specific pathogens and resistance genes. Several tests therefore have to be run to identify the disease-causing pathogen and work out the most appropriate treatment. This is time-consuming and expensive.

A new affordable, simple and quick diagnostic that can be used at the point of care is now on the horizon that can address the challenge. The diagnostic is being developed by Ankur Mutreja and colleagues based at Cambridge University. Designed for LMIC countries, the diagnostic consists of a rapid AMR kit packaged into a portable hand-luggage-sized suitcase.

Modeled on a diagnostic kit being trialled for cholera in India and Malawi (Mutreja et al), the diagnostic kit has the advantage that it can be used anywhere in the world because it is powered by a solar panel built into the suitcase. This means that it can be easily set up and put into operation in remote areas as well as in places with good laboratory facilities. It also provides results within 2-4 hours, which is critical to avoiding the prescription of unnecessary antibiotics.

The diagnostic kit includes a portable PCR, to amplify the DNA in a patient’s sample, and a detection dipstick. A number of molecular probes are attached to the dipstick. These can detect over 100 different variants of 16 highly prevalent antibiotic resistance genes across 8 different classes of commonly used antibiotics. The probes have been designed based on high-resolution whole genome sequencing data.

The test has several advantages. Firstly, unlike in conventional tests, it can detect a range of antibiotics resistance genes without needing to first identify the pathogen. Secondly it is highly dynamic and customisable because the probes on the dipstick can be quickly changed to detect a particular range of antibiotic-resistant genes found locally. These genes vary considerably from country to country and even between hospitals. And they change over time. Thirdly, its results can be easily read by a healthcare worker with minimal training. A mobile phone is also included in the suitcase which allows for the results to be uploaded to a centralised surveillance system to track the spread of AMR.

Able to be deployed both inside and outside the hospital and in remote areas, the diagnostic kit tests a sample for AMR at a fraction of the cost of other molecular diagnostic instruments. Such a reduction in the cost of testing will be invaluable for poor countries where AMR is particularly high. The Cambridge diagnostic is just one example of the type of affordable point-of-care diagnostics that could emerge in the future. These diagnostics are crucial if the world is to move away from using broad-spectrum antibiotics and the over-prescription or futile use of these drugs.

For LMIC countries, access to affordable diagnostics is particularly needed as these are the areas hit hardest by AMR. Inadequate sanitation, poor healthcare services and ability to buy antibiotics over the counter are major contributors to the problem. Many poor countries also have a high prevalence of infectious diseases, such as malaria, tuberculosis and HIV which in recent years have become drug resistant. Both the UN and WHO warn that the incidence of infectious diseases in such places could worsen as a result of the disruption to healthcare services, such as ensuring continuation of treatment and routine vaccination, caused by the COVID-19 pandemic (WHO).
Click here to see a transcript of the interview with Dr Ankur Mutreja.

References

Mutreja, A, et al (7 Aug 2017) 'Evidence for multiple waves of global transmission within the seventh cholera pandemic', Nature, 4777/7365, 462–465.Back

WHO (15 July 2020) 'WHO and UNICEF warn of a decline in vaccinations during COVID-19'.Back