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)
Isolate and identify bacteria or yeast causing bacteremia or fungemia.
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.
Two blood culture sets from different anatomic sites should be submitted to detect suspected bacteremia or fungemia. Draw blood before initiating antibiotic therapy if possible. Invert BacT/Alert bottle to mix with blood and broth thoroughly. Do not refrigerate. For optimum recovery, send immediately or store BacT/Alert bottle at room temperature and send within 18-24 hrs. A maximum of 3 blood culture sets will be accepted within a 24 hr period. If an unacceptable specimen is received, the client will be notified before disposal of the original specimen. Collection: Clean venipuncture site with soap and water if soiled. Wipe with 70% alcohol and allow to dry. Place swab containing an iodoform solution on the venipuncture site and apply in overlapping circles peripherally to obtain a diameter of 4 inches. Allow to dry 2 minutes before performing venipuncture. Do not palpate venipuncture site after preparation. If the patient is sensitive to iodine, alcohol alone may be used. Draw required amount of blood into syringe and transfer to blood culture set. To inoculate bottles, remove protective top from bottle, swab with 70% alcohol and air dry before puncturing. Do not add air to bottles. Label each bottle individually with patient's name, registration number and anatomic site of blood draw. Please do not put label on bottom of bottles or across two bottles since this interferes with loading bottles on the instrument. Additional Instructions:1. Fever of undetermined origin: obtain 2 separate blood cultures initially and 2 more 24-36 hrs later collected 1 hr before the expected temperature elevation. 2. Acute endocarditis: obtain three separate blood cultures during the first 1-2 hrs of evaluation and begin therapy. 3. Subacute endocarditis: obtain 3 blood cultures on day 1. If all are negative 24 hrs later, obtain 3 more. 4. Filamentous fungus (e.g., Histoplasma or Aspergillus sp.) suspected: send isolator tube for fungus blood culture (Blood Culture, Fungus). 5. Mycobacterium sp. suspected: send ia BacT/Alert MB bottle for an AFB blood culture (Blood Culture, AFB). 6. Quantitative culture for bacteria required: see Blood Culture, Quantitative.
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.