What Are Some New Technologies to Detect Antimicrobial Susceptibility & Resistance?

Romney Humphries, PhD, D(ABMM), section chief of Clinical Microbiology at the University of California, Los Angeles, discusses new technologies to detect antimicrobial susceptibility and resistance that are currently under production.

Interview Transcript (slightly modified for readability)

“Today, we have a lot of new technologies in development to detect antimicrobial resistance. A lot of focus has been placed on detecting resistance, but, really, the ability to detect susceptibility is equally important. The traditional methods that we use today are methods that were developed in the 1970s & 1980s and so it’s well past time for newer technology.

Ideally, a technology would be really rapid so that we can detect resistance and susceptibility in our patients as soon as possible. Ideally, at the bedside. In this way, you could tailor therapy to the patient’s specific infection, right off the bat, rather than starting on very broad-spectrum therapy and having to de-escalate or escalate as susceptibility or resistance is detected.

This being said, using a phenotypic method is really important because it can accurately detect susceptibility. In this way, you observe how the bacteria behaves in the presence of the antimicrobial.

There are several new technologies in development, which is very exciting, that do this in a much more rapid way than the traditional methods that we use today. (Which, from collection of a patient’s specimen, to results, can be up to 5 days.) These methods are much more rapid.

The most recent [technology] is [developed by] Accelerate Diagnostics. They have a system called the pheno system (http://acceleratediagnostics.com/accelerate-pheno/) and it does a susceptibility test directly from a positive blood culture. This method reviews the performance of the antimicrobial against the organism in real-time through microscopy. You’re actually imaging the cells and watching how they behave. They can do a susceptibility test within 6.5 to 7 hours.

Another method that is further along in development is through a company called LifeScale (https://www.lifescaleast.com/). They actually weigh the bacteria through the use of a microfluidic channel with a cantilever and so as the organisms one-by-one enter through this channel, they cause a change in the cantilever vibrations so [lab technicians] can count the number of organisms. Of course, if the antimicrobial is killing the bacteria, there will be fewer organisms, and if it’s not, there will be lots of organisms as they continue to grow.

Both [of] those technologies we expect to see in the next year or two coming to the clinical labs.

There are several other technologies that have been developed more to identify bacteria rapidly, but could be adopted to do a susceptibility test. Two [of these] include the BacterioScan method (http://bacterioscan.com/tag/laser-scattering-method/), which is an optical density measurement that counts bacteria. Again, you could count [the bacteria] in the presence of an antimicrobial, after a given time, to see if there is a reduction or an increase in the number of organisms, meaning they are either susceptible or resistant to the antimicrobial.

Another technology has recently been acquired by Roche that evaluates the viability of an organism, or whether it’s alive or dead, based on its ability to take up a gene which is delivered through a bioparticle that they engineer [https://www.rochemicrobiologytests.com/healthcare-associated-infections/innovative-solutions.html]. When [the bacteria] acquire this gene, it gives them the ability to produce light. You look for bacteria being alive [by their] ability to generate light, and as they die, they are no longer able to generate the light, and so the lights go off as the organism is killed by the antimicrobial. These bioparticles can be very specific to a given species of bacteria, or they can be much more broad and look at a whole family of bacteria, like the Enterobacteriaceae, for example.”