FDA Okays Novel Blood Infection, Antibiotic Sensitivity Test

The FDA recently approved the marketing of the PhenoTest BC Kit, which is the first test to identify organisms causing bloodstream infections and can determine which antibiotics can effectively treat the infection, according to a press release.

The novel test is able to cut down the time to treatment, which can improve patient outcomes and prevent the administration of unnecessary antibiotics.

Bloodstream infections caused by bacteria or yeast can occur in patients regardless of age, but are more serious among those with weakened immune systems, the elderly, and infants. Since these infections can lead to septic shock and death, prompt and effective treatment is important.

Traditional identification and antibiotic sensitivity tests can take up to 48 hours after a blood culture detects an infection, while the PhenoTest BC Kit only takes 1.5 hours, according to the FDA. For certain infections, the test can also provide guidance regarding effective treatment options 6.5 hours after initial detection.

In total, the test can identify 14 species of bacterial and 2 species of yeast that cause bloodstream infections, and can determine antibiotic sensitivity of 18 drugs, as deemed appropriate.

Notably, the PhenoTest BC Kit can also identify 2 signs of antibiotic resistance, which has become a widespread problem across the world.

The test measurers the similarity of the pathogen’s genetic material to DNA known to be distinctive of a certain bacteria or yeast. When the organism is identified, it is mixed with antibiotics, and the growth is observed by time-lapse images, the FDA reported. If the organism does not grow, the tested antibiotic may prove effective in treating the infection.

The FDA reviewed data for the test through the de novo premarket review pathway, which is a regulatory pathway for low- to moderate-risk devices that are not equivalent to marketed devices to develop special controls to assure safety and efficacy, according to the press release.

The marketing approval was based on the FDA’s review of a clinical trial including 1850 positive blood cultures, where the PhenoTest BC Kit correctly identified a bacterial or yeast infection with more than 95% accuracy. The antibiotic sensitivity component of the test was also observed to be accurate, compared with traditional testing methods, according to the FDA.

Risks associated with the test include false positive results, which can impact treatment. The FDA advises that results from the PhenoTest BC Kit should be interpreted with additional laboratory testing, according to the press release.

"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, PhD, director of the Office of In Vitro Diagnostics and Radiological Health at the FDA’s Center for Devices and Radiological Health.