Rapid Test for Antibiotic Sensitivity in Blood Infections Approved by FDA

The US Food and Drug Administration just announced that it is allowing the marketing of a new test kit for bloodstream infections. According to the press release, “This is the first test to identify organisms that cause bloodstream infections and provide information about which antibiotics the organism is likely to respond to (antibiotic sensitivity).” As such, the test will be used to guide which antibiotics should be recommended to treat bacterial infections.

"By identifying organisms and knowing earlier which antibiotics the organism is likely to respond to, health care professionals can treat patients with bloodstream infections more appropriately," said Alberto Gutierrez, Ph.D., director of the Office of In Vitro Diagnostics and Radiological Health at the FDA’s Center for Devices and Radiological Health in the press release.

According to the press release, the PhenoTest BC Kit, which is performed on the Pheno System, “can identify bacteria or yeast from a positive blood culture in approximately 1.5 hours. For certain organisms, the test also provides important information to guide treatment recommendations in approximately 6.5 hours after the organisms are detected from blood cultures.”

In addition, the test is able to “identify 14 different species of bacteria and two species of yeast that cause bloodstream infections, while also providing antibiotic sensitivity information on 18 selected antibiotics for a subset of the identified organisms as appropriate. The test will also identify the presence of two indicators of antibiotic resistance.”

The test utilizes the organism’s own genetic material and compares it to the DNA of a known bacteria or yeast to identify the organism present in the blood sample. After identification, the organism is then “mixed with antibiotics and the growth of the bacteria is measured by time-lapse images.” If the no organism growth is observed in the presence of the antibiotic, then that antibiotic is provided as a possible choice for treatment.

In a clinical study of 1,850 blood cultures, the test was shown to provide the correct identification of a given bacteria or yeast in a positive blood culture over 95% of the time. In addition, the antibiotic sensitivity tests were also accurate.

The FDA notes that, “risks associated with use of the PhenoTest BC Kit include false positive findings, which can occur when an individual not infected with organisms that cause bloodstream infections receives a test result that incorrectly indicates that he or she is infected. Results obtained from the test should always be interpreted alongside additional laboratory test results.”

The PhenoTest BC Kit and the Pheno System are manufactured by Accelerate Diagnostics Inc. in Tucson, Arizona.

Similar tests may be on the market in the coming months and years. Recently, a rapid test for bacterial infections won the Horizon Prize in Europe. The prize was awarded to MINICARE HNL for a “finger prick test” that allows for the rapid detection and diagnosis of a bacterial infection in under ten minutes. “Within minutes, the new test is able to differentiate between viral infections that don’t need antibiotics, and acute bacterial infections that might need them; the results are then displayed on a handheld analyzer.”

With antibiotic resistance rates continuing to rise and increased focus on the appropriate use and prescribing of antibiotics, these new tests are paving the way to helping healthcare practitioners make more informed decisions on the best treatments for their patients.