Test Overview

Test Methodology

BacT/Alert Blood Culture System
Verigene® Gram-Positive Blood Culture Nucleic Acid Test (BC-GP)
Verigene® Gram-Negative Blood Culture Nucleic Acid Test (BC-GN)

Test Usage

Isolate and identify bacteria or yeast causing bacteremia or fungemia.

Reference Range*

No growth

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Test Details

Days Test Performed

Daily, 24 hrs

Analytic Time

Preliminary results are reported in 24 hours. Negative cultures are reported in 5 days. The health care provider will be notified of initial positive cultures and Gram stain result. Verigene Blood Culture Nucleic Acid Tests will be run on the first positive set of bottles in an episode of bacteremia. Results will typically be available 3-6 hours after the time of Gram Stain notification.

Soft Order Code


MiChart Code

Toxicology Screen, Blood



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Specimen Requirements


Aerobic or Anaerobic Culture bottle

Normal Volume

10 mL into each bottle. DO NOT OVERFILL.

Minimum Volume

1 mL per year of age (pediatric patients)

Additional Information

Routine blood culture is used to detect aerobic and anaerobic bacteria and yeast. The BacT/Alert Blood Culture System monitors blood cultures continuously for carbon dioxide production by microorganisms. Positive signaling bottles are gram stained to verify positive status. Conventional culture will be performed on all positive bottles. Test includes susceptibility testing of potentially pathogenic organism(s) at an additional charge unless specifically declined.

The first positive set of bottles will be tested using the Verigene Blood Culture Nucleic Acid test. This assay identifies the pathogens and antibiotic resistance mechanisms listed below. These are interim results that may be updated based on conventional culture results. In mixed cultures, Verigene may not identify all the detectable organisms in the specimen, depending upon the concentration of each target present. In addition, conventional culture may be required to assign a resistance determinant to a specific pathogen. There is a risk of false negative results due to sequence variants in the bacterial targets of the assay.
Verigene tests for the following organisms and Resistance markers:
Gram Positive organisms: Staphylococcus species, Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus lugdunensis, Streptococcus species, Streptococcus anginosus, Streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus agalactiae, Enterococcus faecalis, Enterococcus faecium, Listeria species.
mecA (methicillin), vanA (vancomycin) and vanB (vancomycin) resistance determinants

Gram Negative organisms: Acinetobacter species, Citrobacter species, Enterobacter species, Proteus species, Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Pseudomonas aeruginosa.
CTX-M (ESBL), IMP (carbapenemase), KPC (carbapenemase), NDM (carbapenemase), OXA (carbapenemase), VIM (carbapenemase) resistance determinants

Limitations of Verigene Test performance:
• The assay does not differentiate Staphylococcus spp. other than Staphylococcus aureus, Staphylococcus epidermidis and Staphylococcus lugdunensis.
• The assay does not differentiate Streptococcus spp. other than Streptococcus agalactiae, Streptococcus anginosus group, Streptococcus pneumoniae and Streptococcus pyogenes.
• Verigene will not distinguish Escherichia coli from Shigella spp.
• Verigene can only detect OXA types belonging to groups 23, 40, 48 and 58.
• Certain strains of Streptococcus that are genetically homologous to S. pneumoniae, but currently classified as S. mitis, will cross-react with Streptococcus pneumoniae probes. Therefore, S. pneumomoniae will be reported as S. pneumoniae/mitis
• K. variicola is not detected by Verigene, and is difficult to distinguish from K. pneumoniae by conventional culture. Isolates suggestive of K. variicola will be reported as Klebsiella spp. at the time of conventional culture.

• The following additional cross reactivities may occur:
o Lactococcus spp. strains could cause a false positive “Streptococcus” detected result.
o Aerococcus spp. strains could cause a false positive “Staphylococcus” detected result.
o On rare occasions, both a “K. oxytoca Detected” result and a “K. pneumoniae Detected” result may be obtained when Klebsiella pneumoniae is present in the specimen.
o C. amalonaticus may yield false negative results
o Kluyvera ascorbata, Raoultella ornithinolytica, Raoultella planticola, and Cedecea davisae cross-react with Verigene Klebsiella oxytoca probes, which will cause a false positive “K. oxytoca Detected” result.
o Leminorella grimontii, Enterococcus raffinosus and Candida parapsilosis cross-react with Verigene CTX-M probes, which will cause a false positive “CTX-M Detected” result.

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