Accelerating Precision Medicine in Antimicrobial Therapy: The MultiRapid ATB NP Test for Combatting Multidrug-Resistant Enterobacterales

A culture change.. with a rapid culture

Antimicrobial resistance is quickly becoming one of the biggest public health challenges worldwide. It is threatening the effectiveness of antibiotics, which have been a critical part of modern medicine for decades. Among the most troubling contributors to this issue are carbapenem-resistant Enterobacterales (CRE) which can cause severe infections with high mortality rates particularly in people with weakened immune systems. With cases of CRE rising, it has become clear that we need better ways to diagnose and treat infections caused by these bacteria. To address this, scientists have developed several powerful antibiotics, including combinations like ceftazidime–avibactam (CZA), meropenem–vaborbactam (MEV), and imipenem–relebactam (IPR), along with a newer cephlosporin called cefiderocol (FDC). But resistance to these drugs is also becoming a problem. This happens due to factors like bacterial mutations, increased activity of efflux pumps that expel antibiotics, or changes in bacterial membranes that prevent drugs from working effectively. Because of this growing resistance, it is more important than ever to figure out quickly which antibiotics will still work against a specific infection.

Traditional methods for testing antibiotic susceptibility, like broth microdilution are dependable but slow and can take 16 to 24 hours to obtain the results. Unfortunately, in severe infections, that delay can make a huge difference, as every hour counts. There is an urgent need for faster diagnostic tools to guide treatment decisions, avoid delays in starting the right therapy, and reduce the overuse of broad-spectrum antibiotics, which drives resistance even further. Recognizing this need, new research paper published in International Journal of Antimicrobial Agents and conducted by Otávio Hallal Ferreira Raro, Maxime Bouvier, Auriane Kerbol, Laurent Poirel, and led by Professor Patrice Nordmann from the University of Fribourg in Switzerland/Swiss National Reference Center for Emerging Antibiotic resistance created the MultiRapid ATB NP test. This innovative test can determine susceptibility and resistance to CZA, MEV, IPR, and FDC in just three hours. What makes this test even more exciting is its simplicity and adaptability for routine use in microbiology labs and by this can be a game-changer in the fight against antimicrobial resistance without the need of any investment in additional equipment

To make sure the test would work across a range of real-world scenarios, the researchers used a collection of 78 different bacterial strains that came from the Swiss National Reference Centre for Emerging Antibiotic Resistance. These isolates were a mix of different resistance mechanisms, including those caused by KPC, NDM, OXA, and CTX-M β-lactamases, which are known to make bacteria harder to treat. Some strains had multiple resistance mechanisms, which made the testing even more challenging. But that’s exactly what they wanted to test: whether the MultiRapid ATB NP test could handle these tricky cases. The team designed the test to work by detecting bacterial growth through a color change. Essentially, the test measures how bacteria metabolize glucose in the presence of antibiotics. When bacteria grow, they release acid, which causes the medium to shift from red to yellow. This simple color change acts as a clear indicator of whether the bacteria are resistant to the antibiotic in question. The researchers used a 96-well microplate system, where each well contained different antibiotic combinations or control solutions, and they fine-tuned the antibiotic concentrations to make sure the test would accurately differentiate between resistant and susceptible bacteria. The authors found that the MultiRapid ATB NP test had 97.0% sensitivity, 97.7% specificity, and 97.4% accuracy—pretty much on par with the gold-standard method of broth microdilution, but with a huge advantage: the results were ready in just three hours. That is a big improvement over the 16-24 hours typically needed for the standard method, and it could really make a difference in getting patients the right treatment faster. That said, the test was not without its minor limitations. In some cases, such as with a Klebsiella pneumoniae strain showing borderline resistance to CZA, there were a few errors. But even with these small discrepancies, the test was able to pick up on complex resistance patterns, like those involving NDM enzymes. One of the most striking findings was how well the test worked in cases where bacteria had multiple resistance mechanisms. For example, a strain of E. coli carrying the NDM-5 enzyme resisted all the antibiotics tested—except for cefiderocol. This ability to spot resistance in such complex cases could help doctors make more informed choices about treatment especially in critical situations.

In conclusion, the research led by Professor Patrice Nordmann and his team is a significant advancement in addressing the global crisis of antimicrobial resistance, particularly the threat posed by CRE infections. With the faster results of MultiRapid ATB NP test, it helps doctors move from guesswork to precision care and initiating the most suitable treatment much earlier. This not only increases the chances of survival for critically ill patients but also prevents the overuse of broad-spectrum antibiotics, which is one of the main drivers of resistance worldwide. What makes the MultiRapid ATB NP test especially valuable is how practical and accessible and relies on simple materials, such as a 96-well microplate and an easy-to-read color change to signal results. Therefore, the test can be implemented anywhere globally even in facilities with limited infrastructure. Another important and unique aspect of this test is that it works by measuring how bacteria actually behave in the presence of antibiotics which sets it apart from molecular tests that focus on detecting specific genetic markers. Moreover, because resistance often arises through unpredictable or combined mechanisms—like enzyme overproduction, changes in bacterial membranes, or mutations in proteins—this broader approach ensures that the test remains effective even against emerging resistance patterns. Beyond immediate patient care, the new test helps preserve the efficacy of critical drugs for future generations by reducing over use of antibiotics and possibly sets the stage for further innovation, acting as a model for developing rapid diagnostic tools for other types of resistant infections.