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New report helps veterinarians understand their role in getting good susceptibility test results

Chemicals, beakers, breakpoints, Petri dishes full of bacteria—who knows what goes on in a lab?

The Clinical and Laboratory Standards Institute (CLSI) does. They just came out with a new report, VET09—Understanding Susceptibility Test Data as a Component of Antimicrobial Stewardship in Veterinary Settings (VET09), to help veterinarians better understand antimicrobial culture and susceptibility test results as well as just what goes on in the lab once you send your samples in.

CLSI is a not-for-profit membership organization that creates best practices for clinical labs.

The report discusses antimicrobial susceptibility testing (AST) and provides veterinarians with background information about laboratory processes, including how AST is performed, reasons a veterinarian might not want to perform it, and how AST results are assessed by a laboratory.

Virginia Fajt, DVM, PhD, DACVCP, a clinical associate professor of veterinary physiology and pharmacology at Texas A&M University and chair of the CLSI subcommittee that wrote the report, told NEWStat that VET09 can help veterinarians understand exactly what happens after they ship off their specimens.

“There’s a process flowchart in the document that identifies where things can go wrong,” Fajt said. If you want to get the best information you can from the lab, you’ll find helpful pointers on the role the veterinarian plays in the process—[such as] accurate presumptive diagnosis, sample collection, sample transport, and the veterinarian’s interpretation of the results they get back.

Fajt said that understanding what the laboratory is responsible for is helpful for a veterinarian because it clarifies their own role in the process, primarily in submitting samples, understanding what tests can be run and what tests can’t, understanding which tests might be run automatically and which tests might need to be requested specifically.

For example, say a veterinarian has a dog whom she thinks might have a skin infection, so she sends a sample to the lab so that they can confirm what the bacteria is and then perform susceptibility testing on the bacteria.

For that to happen, Fajt said, the veterinarian has to take a good sample from a good location and store it properly before sending it to the lab. Once at the lab, the lab is responsible for attempting to isolate what bacteria are present in the sample. And to do that, they have to grow the bacteria, which takes time. Once they isolate individual bacterium, then they would do susceptibility testing on it.

But first they’d need to decide if testing can be performed, or if it even needs to be: “There are bacteria that have highly predictable susceptibility, so there’s no reason to perform the testing because we know what the results are going to be,” Fajt said. “ Or If the bacteria that are grown don’t appear to be pathogenic, maybe they’re opportunist, then the lab might decide to make a reasonable decision not to do susceptibility testing on that.”

Fajt adds that there are other things for which the lab actually doesn’t have an established methodology. “In those cases, testing wouldn’t be done.”

She says it’s important that veterinarians understand all the pieces that go into coming up with a useful and accurate test result.

“There are a lot of places along the way where you can help ensure that the results you get are more accurate, more useful, and more clinically relevant,” Fajt said.

Find out more about VET09—Understanding Susceptibility Test Data as a Component of Antimicrobial Stewardship in Veterinary Settings here.

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