AdvanDx, Woburn, Mass, reports that use of its PNA FISH™ test was associated with an 82% reduction in mortality rates from S. aureus bloodstream infections in the intensive care unit (ICU), a 53% reduction in overall mortality from staphylococcal bloodstream infections, and a significant reduction in antibiotic use, according to a new study published in the latest issue of the Journal of Therapeutics and Clinical Risk Management. The study was undertaken by clinicians in the section of Infectious Diseases at Washington Hospital Center (WHC) in Washington.

The test provides rapid, molecular identification of S. aureus and coagulase-negative staphylococci (CoNS) directly from positive blood cultures in hours instead of days, and helps labs provide fast results that may help guide therapy for patients with bloodstream infections.

 "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, 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.”

During the WHC study period, 202 patients with positive blood cultures containing gram-positive cocci in clusters (GPCC) were enrolled and blindly randomized into a notification group or usual care group. PNA FISH results and information on the identified bacteria for the notification group were reported directly to the treating clinicians, whereas for patients in the usual care group, data were entered into the hospital’s laboratory information system as usual.  

Medical records of enrolled patients were analyzed for demographics, comorbid conditions, location within the hospital, antimicrobial use, length of hospitalization, mortality, and other factors to understand the impact of the test results on patient care and outcomes. 
Data comparison for notification of PNA FISH (NPF) group versus the usual care (UC) group:

•    Total of 202 patients enrolled in study; 101 in NPF group versus 101 in UC group
•    61 patients with S. aureus; 32 in NPF group versus 29 in UC group
•    141 patient with CoNS; 69 in NPF versus 72 in UC group
•    44 patients in ICU versus 158 in non-ICU
•    53% reduction in overall mortality; 8 deaths in NPF group versus 17 deaths in UC group
•    80% reduction in mortality rate for ICU patients; 10% (2 deaths) for NPF group versus 48% (11 deaths) for UC group
•    82% reduction in mortality rate for ICU patients with S. aureus; 10% for NPF group versus 56% for UC group
•    67% reduction in median antibiotic use after notification of results; median of 1 day for NPF group versus 3 days for UC group
•    100% reduction in median antibiotic use for CoNS patients after notification of; 0 days for NPF group versus 2.5 days for UC group
•    Trend toward $19,441 reduction in median hospital charges; $72,932 median charges for NPF group versus $92,373 for UC group

Some 350,000 patients annually contract bloodstream infections, causing more than 90,000 unnecessary deaths and significant costs to the health care system. The infection is detected when a culture of the patient’s blood turns positive with bacteria and yeast.

Bloodstream infections due to staphylococcus bacteria are a leading cause of hospital-acquired infection mortality. The infection is initially diagnosed when a culture of a patient’s blood turns positive with GPCC, indicative of staphylococci. 

Because conventional lab identification methods can take 48 hours or longer, treating clinicians cannot determine whether the blood culture was positive due to true infection, requiring aggressive antibiotic therapy, or due to blood culture contamination with CoNS, a group of common skin bacteria that don’t require antibiotic therapy. As a result, patients with true infections are sometimes undertreated, and patients with contaminated blood cultures are often unnecessarily treated with antibiotics.   

AdvanDx is a provider of advanced molecular diagnostic products for the prevention, diagnosis, and treatment of life-threatening, bacterial infections.