Advancements in the Field of Blood Culture Testing

Segment Description: Melvin Weinstein MD, professor of medicine, pathology, and laboratory medicine, chief of the Division of Infectious Diseases, Allergy, and Immunology, and co-director of the Microbiology Laboratory at Rutgers Robert Wood Johnson Medical School, to discusses the emerging technologies that will advance the field of blood culture testing.

Interview Transcript: (modified slightly for readability)

Contagion®: Can you speak to some of the newer technologies that are emerging in blood culture testing?

Melvin Weinstein, MD: The newer technologies are mostly molecular-based; they are either single-plex or multiplex Polymerase chain reaction (PCR) assays or if they’re not PCR, they are other DNA amplification techniques. There are assays that target specific organisms like Staphylococcaceae; the GeneXpert Staph SR assay, can differentiate methicillin-susceptible from methicillin-resistant Staphylococcus aureus from non-Staph aureus isolates and do that in approximately an hour, directly out of a positive blood culture model.

There are also new assays from BioFire, which is called the BCID (blood culture identification) assay, which has 27 different targets—multiple gram-positive targets, gram-negative targets, and also several Candida targets—and can detect the Klebsiella pneumoniae carbapenemase (KPC) and those results are also direct from a positive blood culture and you will get your results within about 1 hour.

There’s a similar technology, similar in concept at least, from Luminex, it’s called the Verigene; that has 30 targets—again gram-positive targets, gram-negative targets—and that technology can provide results for 6 different resistance genes for gram-negatives of the CTX-M-ESBL (CefiTaXime Extended Spectrum Beta-Lactamase), the KPC, and other carbapenemases, and also, for gram-positives, it detects the mecA gene, and also the VanA and VanB genes that confer resistance to vancomycin in enterococci.

Not yet FDA approved, but approval [is] expected, for a new, similar-in-concept system from GenMark which will have somewhere in the range of 65 to 70 different targets—so many more bacterial strains, 5 or more fungal strains—including cryptococcosis and fusarium. That system will be very interesting when it becomes available.

There is yet one additional system that is not molecular that is growth based, it’s called the Accelerate Pheno, which detects 8 gram-positive organisms, 8 gram-negative organisms, 5 Candida species, and provides a phenotypic susceptibility result, so essentially a full-range of susceptibility results and it does the identification in approximately 1 hour and a half and provides the susceptibility results in about 7 hours.