The following is from the text I sent to Podiatry Today Magazine for an upcoming feature they are planning on Innovations in Podiatry. I really feel that molecular diagnosis of infection has the potential to change the way we diagnose and ultimately treat lower extremity infections. The company I discuss in the article below, Diatherix, has a unique technology that allows the identification of up to 25 organisms from a single specimen and a single run of the test yielding results in just a few hours. Just for full disclosure, although I have met with the CEO of the company to discuss the technology I have no financial interest or other conflicts at this time:
The current standard for making a bacteriologic diagnosis of a lower extremity infection is the use of a culture and sensitivity. The problem with this test is that it may take several days to obtain a result while the patient has been placed on empiric antibiotic therapy that may be either too broad or too narrow spectrum. Although Polymerase Chain Reaction (PCR), to look at the DNA of the organisms found on a specimen, has been used for a number of years to rapidly identify the bacteria, it has been limited mostly to reference laboratories and is hindered by usually only being able to identify one organism at a time. This is changing with the use of Target Enriched Multiplex-PCR (Tem-PCR) which has the ability to identify up to 25 or more organisms with a single sample and to do it within just a few hours. A company based out of Huntsville, AL, Diatherix, is now commercializing this technology so that any physician in an office or wound center can order this test. The clinician receives swabs and transfer materials, including overnight mailers from the company. They take a specimen, as they would a standard C&S; place it in the mailer to Diatherix which receives it the next morning. By that afternoon a result is communicated to the clinician including the identity of the organism, its relative frequency compared to other bacteria found in the specimen and any genetic markers for resistance, such as the presence of the mecA gene indicating MRSA.
By accurately identifying disease-producing pathogens early, Tem-PCR results can assist physicians in forming a more accurate diagnosis. This provides them the opportunity to accurately diagnosis the condition which leads to the appropriate treatment rather than treating empirically. By enabling physicians to link diagnostics to therapeutics, Tem-PCR results can assist by eliminating the inappropriate use of antibiotics eliminating unnecessary treatments, reducing the development of genetic drug resistance, potentially reducing cost of therapy and providing a better patient outcome.
The Tem-PCR technology provides multiplex amplification of genomic material from multiple pathogens with greatly increased sensitivity compared to standard multiplex PCR. Standard multiplex PCR in general cannot amplify multiple pathogens in a single analysis due to each set of primers requiring differing optimum conditions for best amplification. Tem-PCR works around this by essentially turning the multiplex into a singleplex reaction needing one primer set and one set of optimum conditions so that the best amplification can be obtained. This allows more results from a single sample as a benefit of Tem-PCR over both singleplex PCR and qPCR (real time PCR).
Three significant benefits of producing multiple results from a single sample are being able to accurately identify pathogens causing infection in a rapid fashion, the identification of co-infections and the identification of genetic drug resistance. If a patient presents with a wound that is not healing a physician will perform a culture in order to identify the pathogen or pathogens present. At this point the physician will often treat the symptoms empirically due to the multitude of pathogens that could be causing the infection. If the patient is on antibiotics at the time the sample is taken for culture there is a very good chance the culture will be negative which leaves the physician to continue empiric treatment. If on the other hand the physician had obtained a sample to be performed by Tem-PCR up to 25 pathogens would be tested including genetic drug resistance providing the physician with definitive information leading to proper treatment.
Diatherix claims that the test is covered by most insurance companies.
