The Food and Drug Administration (FDA) has cleared Cepheid’s Xpert Carba-R Assay, the first test to detect specific genetic markers associated with bacteria that are resistant to carbapenem antibiotics. The Xpert Carba-R Assay is intended as an infection control aid that can be used with other clinical and laboratory findings. 

The superbugs, also known as carbapenem-resistant Enterobacteriaceae (CRE), are currently identified by growing bacteria from fecal material cultures. Then they undergo antimicrobial susceptibility testing to determine in vitro susceptibility, which may take up to 4 days. Additional testing may be required to confirm the presence of carbapenemase, the enzyme produced by CRE. 

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The Xpert Carba-R Assay, however, tests patient specimens directly taken from rectal swabs and tests for the presence of five different genetic markers produced by carbapenemase.  Accurate results can be delivered as fast as 48 minutes, allowing clinicians to assess high-risk patients for colonization status at or prior to admission. The Assay does not detect all types of carbapenemase genes, the bacteria, carbapenemase activity, or other possible non-enzymatic causes of carbapenem resistance; it only tests for genetic material. 

The FDA’s approval was based on data from two clinical studies. One prospective study (n=755) evaluated rectal swabs from patients in hospitals or long-term care facilities to compare results from the Xpert Carba-R Assay with results from reference cultures and automated real-time polymerase chain reaction (PCR) sequencing. The second study used 432 artificially prepared rectal swabs containing specific levels of bacteria with the genes detected by the test. The results from both studies demonstrated similar performance between the Xpert Carba-R Assay and culture method.

The Xpert Carba-R Assay runs on Cepheid’s GeneXpert System. The Assay is anticipated to launch in July.

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