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Screenshot of the ISDD in use.

A new type of blood culture system that diverts the first few drops of blood taken from a patient drastically reduces the risk of contamination, a new study shows.

The initial specimen diversion device (ISDD) called SteriPath, made by Magnolia Medical Technologies, is a pre-assembled, sterile blood culture system designed to divert and sequester the initial 1.5 to 2 mL of blood taken during a culture to prevent bacteria and skin cells from contaminating the sample.

Researchers at the University of Nebraska Medical Center, where the study was conducted, noted that contamination rates among blood cultures range from .6 percent to six percent.

While this range may not seem too significant on the surface, Mark Rupp, professor and chief of the UNMC Division of Infectious Diseases, explained to Laboratory Equipment that 30 million blood cultures are drawn in the U.S. per year, so even a contamination rate of just two percent equates to about 600,000 false-positive events, which result in unnecessary antibiotic treatment and added laboratory expenses.

About 30 to 40 percent of patients with contaminated blood samples are prescribed antibiotics they don’t need, and can cause them to have to get another unnecessary blood draw as well.  

“This is fueling the antibiotic resistance problem,” said Rupp.

“False-positive blood cultures increase laboratory costs by approximately 20 percent, are associated with a nearly 40 percent increase in antibiotic charges, are treated with antimicrobials up to one half of the time, extend the length of hospital stay by up to five days,” wrote the study authors, in the journal Clinical Infectious Diseases.

Nearly 1,000 patients who visited the university’s emergency department were enrolled in the study. Each participant consented to having two vials of blood drawn – one using the ISDD device, and the other was done using the standard technique.

The team found that the ISDD reduced contamination rates by 90 percent.

According to Rupp, who is also the medical director of the Deptartment of Infection Control & Epidemology at Nebraska Medicine, contamination occurs when the needle penetrates the skin, and drives skin cells and bacteria under the skin, which then mixes in with the blood being drawn.

This contamination still occurs despite standard precaution techniques such as prepping the skin with an antiseptic, using sterile gloves, and ensuring trained phlebotomists are conducting the blood draw.

By separating the first few drops into another chamber, phlebotomists ensure they obtain a pure, sterile sample of blood for testing.

The device can be used for nearly all patients who need blood cultures taken, with the exception of infants or neonates, as they already have a small amount of blood volume, and diverting the first couple milliliters of blood may not be the best option.

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