One might ask, is PCR testing better than cell culture?
And one might get the answer that’s not even comparing apples to oranges. It’s apples to pumpkins! Though, in a limited yet vital subset for diagnosing infection in companion animals, we can directly compare each of these techniques to diagnose the presence of specific bacteria. More importantly, we can use PCR testing to look for antibiotic resistant markers, fingerprints, on each of the bacteria.
Why does the fingerprint of AMR matter?
An AMR genetic marker is a tiny section of the bacterial DNA strand that has evolved to confer a resistant mechanism to one or more of the five classes of antibiotics that are commonly used to fight infection. This marker acts much like a rattlesnake’s tail – a small but powerful defense strategy.
The world is rapidly running out of effective antibiotics due to the increase in bacterial evolution towards antibiotic resistance, and there are multiple stewardship strategies which can slow this down.
One of these is early selection of the correct antibiotic to treat an infection.
PCR (Polymerase Chain Reaction)
LexaGene has developed a one-of-a-kind ‘Keurig-like’ MiQLab™ System that uses PCR to test for these markers in-clinic. To demonstrate the absolute accuracy and power of PCR, our scientists compared the identities of bacteria in a known sample against the exact same sample sent to a commercial reference lab. A MiQLab runs a test in approximately two hours, at the point-of-care, by anyone who has received about an hour of training. It’s that easy.
Culture and Sensitivity Testing (C&ST)
In contrast cell culture work (aka culture and sensitivity testing) is performed in a highly specialized ‘reference’ lab using trained personnel. Samples are often shipped off-site to a reference lab providing an administrative layer of both transportation and receiving. Reference lab staff must be trained to perform high-precision manual agar plating, work under controlled growth conditions, and complete optical recognition of different bacteria. After these complex steps have been done, additional plating must occur with the presence of different antibiotic infusions to determine the resistance of a bacterial strain to an antibiotic. This process can take up to two weeks including shipping and handling. Mistakes are frequent due to human error in the sample preparation as well as shipping. The lengthy time to answer delays the prescription of the correct antibiotic.
LexaGene’s study demonstrated:
- MiQLab successfully detected two bacterial strains in polymicrobial samples in ~2 hours
- Culture and Sensitivity Testing (C&ST) failed to detect equivalent minor pathogen population in individual mixed samples, with final test results taking between 5 – 11 days
- In-clinic MiQLab testing can improve treatment decisions, particularly for polymicrobia infections caused by drug resistant strains.