Last-resort antibiotics: "We can identify carbapenemases within half an hour"

Antibiotic resistance is modern medicine's greatest challenge. Some bacteria only respond to a handful of antibiotics, prompting hospitals to spend a lot of time finding an effective drug. That’s why it is critical for physicians to rapidly identify antibiotic resistance to avoid ineffective treatments.

In this MEDICA-tradefair.com interview, Prof. Axel Hamprecht describes a test that detects bacteria that are resistant to the carbapenems class of antibiotics, and reveals how researchers and hospital facilities can directly build on commercial products to solve urgent problems.

Prof. Hamprecht, what tests do you use to identify antibiotic-resistant bacteria?

Prof. Axel Hamprecht: We typically use phenotypic drug resistance testing to check approximately 99 percent of bacteria for susceptibility or resistance to certain antibiotics. That is to say, we test whether a bacterium culture is able to survive and grow in the presence of one or more antibiotics. The drawback is that this test takes quite a long time, often between 16 and 48 hours.

You and your team have now developed a quicker process that is based on a commercially available test. How does it work?

Hamprecht: This is an immunochromatographic assay that can detect the presence of proteins by using antibodies. This test was developed for the detection of carbapenemases. These are enzymes that inactivate carbapenems, a class of our most effective last-resort antibiotics. Resistances are especially problematic in this setting because it leaves us with extremely limited treatment options. By developing this test, we created a method that identifies carbapenemases directly from positive blood cultures. It works faster than the aforementioned phenotypic drug resistance testing. Our test allows us to identify carbapenemases within half an hour.

Which antibiotic resistance mechanisms can this test identify?

Hamprecht: We can easily identify the four most common carbapenemases in Germany: OXA-48, VIM, NDM and KPC. It is somewhat more difficult to detect IMP-type carbapenemases due to its many varieties. Having said that, this enzyme is not very common in Germany. The four common varieties make up circa 99 percent of all carbapenemases in Germany.

Can this method be applied in clinical practice?

Hamprecht: Essentially yes, although this was only a retrospective test. A prospective study would be practically impossible in Germany, because we thankfully do not have many types of carbapenem-resistant enterobacteriaceae in this part of the world. It would take us a very long time to come up with an adequate number of cases. Having said that, there is a rise of carbapenem-resistant enterobacteriaceae in Greece, Turkey, Italy or Asia for example. That is why we frequently see cases of CRE colonization or infection in patients who underwent medical treatment in these areas of high CRE prevalence. A prospective study would therefore best be conducted in these countries.

From your perspective, what are the biggest future challenges as it pertains to antibiotic resistance diagnostics?

Hamprecht: The fact that there is a dramatic increase in the emergence of antibiotic-resistance gram-negative bacteria such as E. coli and Klebsiella, while we have fewer and fewer effective antibiotics in our arsenal. That's why it is very important for us to identify antibiotic resistance at a more accelerated pace than in the past. There are a multitude of methods in the development stages, which promise even greater benefits.