New test procedure can rev up diagnosis of multi-resistant hospital pathogens

Credit: University of Cologne

Researchers from the University of Cologne’s Faculty of Medicine and the German Center for Infection Research (DZIF) have taken a great step forward by accelerating the diagnosis of multi-resistant hospital pathogens.

The research team used a novel immunochromatographic method, and found bacteria that are resistant to the antibiotic group carbapenemes only within 20 to 45 minutes from blood cultures with 100 percent certainty, whereas the current available test procedures tend to take up to 72 hours. The study was published recently in the journal PLOS ONE.

People who suffer from infections that are caused by gram-negative pathogens like Escherichia coli (E. coli) have a high mortality rate. But so far, the infection has usually been treatable with antibiotics. However with the increased antibiotic resistance of bacteria, also against the group of carbapenems, treatment has become increasingly difficult. Infections which are caused by multi-resistant pathogens that are also resistant to such ‘reserve antibiotics’ are often the reason behind ineffective antibiotic therapy and therefore to higher mortality.

In order to confirm the presence of pathogens such as E. coli in the bloodstream, the methods that are currently being used take 16 to 72 hours to detect antibiotic resistance. Therefore, accelerated diagnostics is therefore an important step towards treating patients with infections caused by carbapenem-resistant bacteria faster and especially towards curbing the spread of the pathogens.

This resistance of gram-negative bacteria is usually caused by enzymes that have the potential to destroy antibiotics, including the carbapenem antibiotics, which are known as carbapenemases. The most common carbapenemases all over the globe are Klebsiella pneumoniae carbapenemase (KPC), New Delhi metallo-betalactamase (NDM) and OXA-48.

This new study analysed the blood samples mixed with carbapenemase-producing bacteria. Three out of the four most common carbapenemases – OXA-48, KPC and NDM – were found directly from the positive blood cultures using only a single test procedure without the research team having to make time-consuming further cultivation on agar plates. The new method developed by the research team is faster, easy to use, and significantly cheaper (approximately 10 euros per test) and can be easily performed in almost any clinical microbiology laboratory.

“With this procedure, we have come a giant step closer to our goal of being able to help patients infected with multi-resistant pathogens as quickly as possible”, said Professor Dr. med. Axel Hamprecht from the German Center for Infection Research and the Institute for Medical Microbiology, Immunology and Hygiene at Cologne University Hospital, who is also the lead author of the study. “In the case of the aggressive pathogens we are confronted with, every minute counts in order to start a targeted therapy. We now have to conduct follow-up studies in order to transfer our findings into clinical practice as quickly as possible.”

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