Rapid Identification of Pathogens Causing Bacterial Septicemia

A molecular based test is now available that will simultaneously identify three Gram-negative bacteria directly from positive blood cultures in less than 90 minutes.

A three-color multiplex assay allows for the identification of Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa from positive blood cultures.

Smears of blood cultures are heat fixed onto microscope slides, a drop of GNR Traffic Light peptide nucleic acid fluorescence in situ hybridization (PNA FISH) probe is added to the smear and then hybridized at 55 °C for 30 minutes.

The GNR Traffic Light PNA probe is mixture of a fluorescein-labeled E. coli-specific PNA probe, a fluorescein and tetramethylrhodamine labeled K. pneumoniae-specific
PNA probe and a Texas Red labeled P. aeruginosa-specific PNA probe.

The slides are then washed for 30 minutes at 55 °C. After which the slides are mounted and visualized with a fluorescence microscope with a FITC/Texas Red filter and 60× oil objective. E. coli is identified as green fluorescent cells, K. pneumoniae as yellow and P. aeruginosa as red. The GNR Traffic Light PNA FISH assay is the latest test from AdvanDx (Woburn MA, USA) and is now available in Europe. It is an addition to their easy-to-use, molecular-based PNA FISH diagnostics platform designed to provide rapid, therapy-guiding results enabling clinicians to provide early, effective therapy for patients with Gram-negative bloodstream infections.

Studies show that providing a 24 hours "head start" on appropriate, narrow-spectrum therapy for Gram-negative bloodstream infections may improve clinical outcomes, reduce antibiotic resistance rates, and reduce the incidences of adverse events. GNR Traffic Light PNA FISH will enable microbiology labs to provide clinicians rapid, accurate Gram-negative pathogen identification results in hours, instead of days. Every year, close to 875,000 patients in the USA contract bloodstream infections, leading to over 150,000 deaths. The infection is detected when a culture of the patient's blood turns positive with bacteria or yeast. Rapid and accurate identification of the specific infecting pathogen is crucial to ensure early and appropriate therapy and save patient lives.

Thais T. Johansen, M.B.A., president and CEO of AdvanDx, said, "The GNR Traffic Light PNA FISH test demonstrates AdvanDx's commitment to developing cutting-edge molecular diagnostic products that provide fast results for these serious infections."

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