DNA sequencing technique IDs blood-borne pathogens cheaply and rapidly

An interdisciplinary research team at the University of Arizona (UA; Tucson, AZ) conducted a clinical study using a DNA sequencing-based technology to identify pathogens causing bloodstream infections—a technique that could slash healthcare costs and save more lives.

The technique—peptide nucleic acid fluorescence in-situ hybridization (PNA-FISH)—rapidly identifies bloodstream pathogens by their genetic code. Results are available within hours instead of days, providing pharmacists and physicians with information they can use to rapidly customize antimicrobial treatment for patients with infections. In the study, rapid reporting of PNA-FISH results cut the mortality of ICU patients with enterococcus or streptococcus bloodstream infections by almost half and slashed mortality from yeast infections by 86 percent. In addition, the intervention resulted in healthcare cost reduction of almost $5 million per year.

PNA-FISH uses fluorescent molecules tagged to genetic sequences that match those in the microbe. When added to a dried drop of blood culture containing pathogens, sequences that find their match inside the microbe stick, while those that don't are washed away. Once the tagged genetic sequences link up, a clinical scientist views the slide under a special microscope that makes the fluorescent tags visible. The microbes' identity is confirmed by the color of their fluorescence.

Led by Donna Wolk, an associate professor at the UA's College of Medicine and division chief of clinical and molecular microbiology in the department of pathology at the UA, the study assessed patients with positive blood cultures admitted to UA Medical Center-University Campus between August 2007 and March 2011. Outcomes and costs for 722 patients were analyzed, of which 344 had PNA-FISH performed. Board-certified clinical microbiologists tested blood cultures and reported PNA-FISH results to infectious disease pharmacists and physicians.

The research team recently presented its results at the 51st Interscience Conference on Antimicrobial Agents and Chemotherapy in Chicago.

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