Published Jul 15, 2024 | 7:00 AM ⚊ Updated Jul 15, 2024 | 7:00 AM
AMR has serious consequences for individuals, healthcare systems, and economies. AMR leads to prolonged hospital admissions, increased healthcare costs, and higher costs in second-line treatments. (Shutterstock)
Imagine our bodies having special soldiers called antibodies, fighting off tiny enemies — germs — when we get sick.
But sometimes, these germs can be clever. If we use the same superhero too much or not in the right way, the germs learn to resist the superhero’s powers. It’s like a boxer knowing his rival’s moves in advance.
Once the enemies know the strategies, the superhero might not be effective because the germs have become resistant. This is what we call Antimicrobial Resistance (AMR), where the germs become too strong for our superheroes (antibodies) to defeat.
AMR makes it harder for doctors to make you better when you are sick. Sometimes, you may get sicker.
A silent pandemic, AMR was associated with 4.95 million deaths in 2019. The World Health Organisation (WHO) reports that one in every five of these deaths occurred in children aged below five, highlighting the acute need to address the crisis.
But to know that there is AMR, you need to get tested but the testing technology either takes time or costs a lot.
India-based researchers at CrisprBits have developed a new test called PathCrisp that can quickly detect antibody resistance. A study published in Medrxiv revealed that this new test could help doctors make faster decisions to treat infections that do not respond to common antibiotics.
Antibiotics like Carbapenems are like super-strong medicines used when others don’t work for serious infections. They are good at fighting many kinds of bacteria.
But there’s a problem: We don’t have cheap and faster tests to know exactly when to use these super-strong medicines. This means that the doctors might use them too often or not in the right way, which can make the bacteria learn to resist the medicine. This is called resistance, and it’s happening with Carbapenems, which is a huge problem for public health.
The WHO says that when bacteria become resistant to Carbapenems, the chance of people dying from these infections is much higher, sometimes even between 26-70 percent. So, it’s important to have effective and faster tests to know when to use these antibiotics, especially in places short of medical resources.
A major reason for this resistance is that some bacteria produce special enzymes called carbapenemases. These enzymes make the bacteria immune to antibiotics.
One of the worst types is called New Delhi metallo-β-lactamase (NDM), which can resist many antibiotics, including Carbapenems. NDM has spread all over the world, especially in India, making it important to detect it early and stop it from spreading.
Several technologies can detect AMR. Traditional tests usually take 2-5 days to provide results. Some commercial tests, like VITEK-2, can provide results in a few hours but are expensive, need large machines, and require pure samples, leading to a turnaround time of 18-24 hours.
MALDI-TOF-based tests can identify pathogens and resistance in a few hours but also need expensive equipment. Molecular tests are another option that is both quick and accurate.
Among these, PCR and qPCR are the gold standards, but they require advanced equipment and techniques, such as qPCR and whole genome sequencing (WGS).
PathCrisp is an innovative molecular diagnostic tool designed for the rapid and precise detection of New Delhi metallo-beta-lactamase (NDM) genes in carbapenem-resistant Enterobacteriaceae (CRE). This tool promises to revolutionise the early detection of antibiotic resistance, addressing a critical need in global healthcare.
The PathCrisp assay, a unique combination of Loop-mediated Isothermal Amplification (LAMP) and CRISPR-based detection, offers a novel solution to the challenges of current diagnostic methods.
Traditional diagnostic tools for antimicrobial resistance require time-consuming and elaborate culture-based testing, often delaying crucial treatment decisions.
PathCrisp, however, provides rapid, accurate results directly from culture samples within approximately two hours, significantly reducing the turnaround time and enhancing clinical decision-making.
Isothermal amplification techniques like LAMP are often recommended because they don’t need special heating and cooling machines and are more sensitive than standard PCR and qPCR methods. However, LAMP can sometimes give false positive results due to its lower specificity.
CRISPR/Cas, known for gene editing, uses an enzyme called Cas and a guide RNA to cut specific DNA sequences. Cas12a, a variant of CRISPR/Cas, can cut single-stranded DNA (ssDNA) and create a glowing signal when it finds its target, making it useful for diagnostics.
In this study, scientists introduced the PathCrisp assay, combining CRISPR/Cas12a and LAMP, to detect carbapenemase NDM, an enzyme that makes bacteria resistant to certain antibiotics.
The PathCrisp-NDM variant uses a fluorescence-quencher ssDNA to show real-time detection within two hours. Compared to the standard PCR method, PathCrisp-NDM was more sensitive and could directly detect bacterial colonies. Overall, PathCrisp-NDM is a specific, sensitive, and rapid diagnostic test that can help treat patients quickly and effectively.
CRISPR is like a pair of scissors that can cut DNA at specific places. There’s a special version called Cas12a that can cut single-stranded DNA when it finds what it is looking for. Scientists can use this cutting action to make a glowing signal, which helps them see if the bacteria are present.
Scientists combined LAMP and CRISPR/Cas12a to create a new test called PathCrisp-NDM. This test can find a specific enzyme (called NDM) that makes bacteria resistant to certain antibiotics. PathCrisp-NDM uses a special DNA piece that glows when cut, showing real-time results in just 2 hours.
The development of PathCrisp involved a multidisciplinary team of researchers from CrisprBits Private Limited, Ashoka University, Sahyadri Hospitals Pvt Ltd, Max Super Speciality Hospitals, Sri Venkateswara Institute of Medical Sciences, and the Sri Sathya Sai Institute of Higher Learning.
Rapid Results: PathCrisp delivers precise results in about two hours, facilitating timely clinical interventions.
High Sensitivity and Specificity: The assay can detect as few as 700 copies of the NDM gene, demonstrating 100% concordance with the PCR-Sanger sequencing method.
User-Friendly: PathCrisp eliminates the need for complex equipment and kit-based DNA purification, using a simple crude extraction method via heating.
Cost-Effective: Designed to be affordable, PathCrisp is poised to become an essential tool in resource-limited healthcare settings, aiding in the fight against antimicrobial resistance.
(Edited by Majnu Babu).
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