Every year, hundreds of thousands of people acquire bloodstream infections in, of all places, the hospital. Doctors will typically treat patients with broad-spectrum antibiotics until they know the exact type of infection, which can take 48 hours in cultured tests.

During that time, patients' conditions can worsen, money for lengthened hospitals stays is wasted or patients may be well enough to go home because initial tests produced false positives.

AdvanDx (Woburn, Massachusetts) has reported a new study that shows use of its PNA FISH test was associated with an 82% reduction in mortality rates from S. aureus bloodstream infections in the ICU, a 53% reduction in overall mortality from staphylococcal bloodstream infections and a significant reduction in antibiotic use.

The rapid test, which currently takes two hours but will be whittled down to 80 minutes in the near future, allows microbiology labs to report identification results to physicians within a few hours of a blood culture turning positive.

"None of the other quick tests for bloodstream infections currently available are 100% specific or reliable. Ours is," Phillip Onigman, director at AdvanDx told Diagnostics & Imaging Week.

Bloodstream infections due to Staphylococcus bacteria are first diagnosed when a culture of a patient's blood turns positive with Gram-positive cocci in clusters (GPCC), indicative of staphylococci. Because conventional lab identification methods can take 48 hours or longer, treating clinicians can't determine whether the blood culture was positive due to true infection, requiring aggressive antibiotic therapy, or due to blood culture contamination with Coagulase-Negative Staphylococci (CoNS), a group of common skin bacteria, that don't require antibiotic therapy.

Because of these delays, patients with true infections are at times under-treated and those with contaminated blood cultures are often unnecessarily treated with antibiotics. PNA FISH provides rapid, molecular identification of S. aureus and CoNS directly from positive blood cultures.

Originally launched in 2003, Onigman said many hospitals and physicians have been slow to adopt the test because of a lack of information and studies that prove the advantages of PNA FISH.

The new study, just published in the Journal of Therapeutics and Clinical Risk Management, was undertaken by clinicians at Washington Hospital Center (WHC; Washington).

During the WHC study period, 202 patients with positive blood cultures containing GPCC were enrolled and blindly randomized into a Notification group or a Usual Care group.

For patients in the Notification group, PNA FISH results and information on the identified bacteria were reported directly to the treating clinicians whereas for patients in the Usual Care group, data were entered into the hospital's lab information system as usual.

"Rapid delivery of PNA FISH data from the laboratory to treating clinicians was associated with reduced mortality in ICU patients," said lead author Shmuel Shoham, MD, of the section of infectious diseases and director of transplant infectious diseases at WHC. "There was also a trend toward reduced length of hospitalization in non-ICU patients with S. aureus, and in patients with blood cultures growing CoNS regardless of location with the hospital. PNA FISH diagnostic tests provide rapid results that enable us to optimize therapy, improve patient outcomes and reduce hospital costs."

The study showed:

A 53% reduction in overall mortality; eight deaths in NPF group vs. 17 deaths in UC group.

An 80% reduction in mortality rate for ICU patients.

An 82% reduction in mortality rate for ICU patients with S. aureus.

A 67% reduction in median antibiotic use after notification of results.

A 100% reduction in median antibiotic use for CoNS patients after notification.

A trend toward a $19,441 reduction in median hospital charges.

For hospitals to begin using the PNA FISH test, Onigman said start-up equipment costs $5,000 and then tests are $36 per slide.

"The resulting savings are big. A Maryland hospital says they are saving an average of $4,000 per patient," he said. "If you can start the right antibiotic sooner, get the patients out of ICU sooner you can save, potentially, $6,000 per day in ICU costs."

There are many instances when a patient could be ready for discharge but a final blood culture is positive, but it's actually been contaminated. "Doctors and hospitals are legally bound to hold the patient and treat them," Onigman said. "Three percent to 10% of some positive blood cultures are contamination. But a positive result to a doctor means he has to put a patient on IV antibiotics. They do that and hold patients unnecessarily. Then they have to redo the culture and the patient has to stay in hospital for an extra week. They put patients through this cycle and they don't even have a real bacteremia. Our test can avoid this."

Last fall, AdvanDx reported that it closed a $15 million Series C financing round from new investor bioMérieux (Marcy L'Etoile, France) and existing investors LD Pensions and SLS Venture.

At the time, the company said the financing would be used to accelerate the commercialization of its product pipeline through its global sales and marketing operations as well as to expand its research and development activities.

The funding followed AdvanDx's report of an exclusive distribution partnership with bioMérieux for its PNA FISH products for positive blood cultures in the U.S. Together with the funding, the distribution partnership secured a significant cash flow stream for AdvanDx.