27 Nov 2020
Dr. Rafael Cantón, Head of the Clinical Microbiology Department at the University Hospital Ramón y Cajal, discusses the rising issue of antimicrobial resistance in hospitals and explains how his team helps clinicians test for antimicrobial susceptibility. In this video interview, Cantón explores the current limitations of antimicrobial susceptibility testing and offers insights into how to reduce antimicrobial susceptibility testing time through techniques such as microscopy, flow cytometry, and calorimetric methods.
My name is Rafael Canton. I'm the head of the Clinical Microbiology Department in a big hospital in Madrid. This is a university hospital and we are doing clinical microbiology for the hospital and also for inhabitants in the surrounding area. One of the most important tasks in the clinical microbiology laboratory is to identify microorganisms.
And when we identify microorganisms, we have to offer the clinicians the possibility to treat these patients and this treatment is with antibiotics. So we perform what we call antibiotic susceptibility testing in the lab. We test different antimicrobials and we offer according to this susceptibility test and this results in the possibility of treating this patient with antibiotics that we have tested in vitro.
Well, unfortunately, we are using a lot of antibiotics. We have infections in the patients, and because we are using these antibiotics, there is a selection pressure on the bacteria. And this is one of the reasons that the microorganism has produced some mechanism to avoid the bacterial effect, the killing effect of the antibiotics over the microorganism.
And this is the reason why the microorganism has antibiotic resistance. When we have the COVID-19 pandemic, we start doing clinical care to the patients that have COVID. And sometimes we forget the other things that we were doing in the laboratory, including, not only antibiotic susceptibility testing but also, for instance, just to track initial bio studies of this multi-track resistant microorganism. But also, most importantly, we didn't have enough time to perform what we call antimicrobial stewardship, which is using the protocols to try to better use antibiotics and to avoid the emergence of antibiotic resistance. Well, it is clear that when we release the antimicrobial susceptibility testing, this result is going to take by a clinician and the clinician is going to adapt the antimicrobial use for this particular patient.
So if we do this in less time, the use of antimicrobial, we have less impact on the spread let's say on the microbial resistance. This has been clearly demonstrated with a series of patients. So the rapid antimicrobial susceptibility testing will have benefits for the patients but also will have benefits for the global spread of antimicrobial resistance.
Well, the most important current limitation of antimicrobial susceptibility testing with the methods that we are using now is the time that we use to release the results. Normally, we grow the microorganisms with antibiotics and we read the test that we are using the next day. So normally we use what we call clinical microbiology an overnight culture and this takes one day.
So this is one of the limitations because the patient stayed with antibiotics that have been used probably. And if the patients need to be changed of this antimicrobial use, it takes time to do. So if we reduce this time, the clinical benefit will be high for the patient. So because we are using the time to release the results, the modern approaches that we are using in antibiotic susceptibility testing are methods that decrease this time of reporting the results.
Whatever we are using, the object is to decrease this time of reporting. So we are using, for instance, microscopic methods. We are using also flow cytometry methods. We are using, for instance, calorie metric methods just to try to release the results even in two hours, but also in less than these two hours.
Well, I think the impact will be on the patient, we'll see a clinical benefit, for instance, less mortality rate. This is difficult to demonstrate in a study. But one thing that probably we will demonstrate is the economical benefit.
If we are using the antibiotics more rapidly to take this decision for the use of antimicrobial science in specific patients, it is well known that the patient will stay less time in the hospital.
So the economic impact will be very clear in the patient. This has been demonstrated for another technique that we have been introduced very recently in the clinical laboratory, for instance, the MALDI-TOF. The MALDI-TOF, the mass spectrometry method, is used for the identification of the microorganism. In the conventional or traditional methods, we used 24 hours for the identification.
Now with the MALDI-TOF is a very rapid identification. It takes minutes to do that. We can release this identification and if we put together this rapid identification with rapid antimicrobial susceptibility testing, we will perform a benefit to the use of these antibiotics in the patient.
And because the patient will treat better, the patient will stay less time in the hospital and we will obtain these clinical benefits in the patient, but also for the economical results of the hospital. Another important benefit will be on antimicrobial resistance because if we are better using the antimicrobial agents, the impact on the selection of antimicrobial resistance will be lower.
So we expect that if we introduce these rapid antibiotic susceptibility testing, the antimicrobial resistance will decrease in the future.
University Hospital Ramón y Cajal in Madrid
Dr. Rafael Cantón is Head of the Clinical Microbiology Department at the University Hospital Ramón y Cajal in Madrid, Spain. Dr. Cantón’s work focuses on the epidemiology of antimicrobials and how this can help to reduce antimicrobial resistance in hospitals.