Evaluation of the Verigene Gram-Positive Blood Culture Nucleic Acid Test for Rapid Detection of Bacteria and Resistance Determinants

Abstract

(2) and is associated with prolonged hospitalization, with higher health care costs (3). The clinical microbiology laboratory plays a vital role in the treatment of patients with bloodstream infections. While current methods for the detection and characterization of bloodstream pathogens can take days, the risk of death from sepsis increases by 6 to 10% per hour from the onset of shock to the start of effective antimicrobial treatment (4).Over 50% of organisms identified in positive blood cultures are Gram-positive bacteria (5). Gram-positive organisms also are common contaminants of blood cultures. Therefore, rapid differentiation of pathogens from contaminants would be clinically useful.The Verigene Gram-positive blood culture (BC-GP) nucleic acid test for investigational use only (IUO) (Nanosphere, Northbrook, IL) is a random-access, automated test that performs nucleic acid extraction directly from positive blood culture media, hybridization onto a microarray, and analysis in 2.5 h. Targets in the assay include Staphylococcus spp., Streptococcus spp., Micrococcus spp., Listeria spp., Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus lugdunensis, Streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus anginosus group, Enterococcus faecalis, and Enterococcus faecium. In addition, if S. aureus or S. epidermidis is detected, then the presence or absence of the mecA gene is reported. Similarly, if E. faecium or E. faecalis is detected, then the presence or absence of the vanA and vanB genes is reported. The BC-GP test was approved by the U.S. Food and Drug Administration (FDA) on 27 June 2012 for the reporting of all IUO targets except Micrococcus spp. (6).We evaluated the performance of the Verigene BC-GP IUO assay in comparison with routine laboratory methods used in the clinical laboratory. A recent evaluation of the BC-GP assay (7) tested blood cultures from a blood culture system (VersaTREK; Trek Diagnostic Systems, Cleveland, OH) that is used by Ͻ10% of U.S. laboratories, while our study utilized the BacT/Alert instrument (bioMérieux, Durham, NC), which is found in ϳ50% of laboratories (N. Safwat, personal communication). Another novel aspect of our study is the assessment of the time from Gram stain result reporting to identification and susceptibility result reporting for current laboratory methods, in comparison to the time for BC-GP results. This research was conducted at the Cleveland Clinic, after approval by the institutional internal review board.(This study was presented in part at ID Week, San Diego, CA, 20 October 2012.) MATERIALS AND METHODSBlood culture samples. The BC-GP IUO test was evaluated with blood cultures submitted for testing at the Cleveland Clinic microbiology laboratory in February to August 2012. Positive aerobic blood culture samples (in BacT/Alert FA bottles [bioMérieux, Durham, NC]) that contained Gram-positive cocci from unique patients were included in the study. Specimens were excluded if multiple morphologies were observed ...

Implementation of a Rapid Microarray Assay for the Detection of Gram-Positive, Gram-Negative and Resistance Determinants: Assessing Performance in a Clinical Laboratory in Bulgaria

“…The gold standard method for pathogen identification in BSI, used also in our laboratory, requires culturing patient blood in an automated continuous monitoring system, resulted as "not detected" which is three times less, compared with the data, obtained in our hands (4). In regards to the oxacillin resistance, Verigene mecA detection and Vitek-2 correlation was reported to be 97-100% [7,8], which is differs from the results obtained in our study, 75.7%.…”

“…FISH (fluorescent in situ hybridization), PCR, MALDI-TOF and sequencing have been implemented for more than a decade [3][4][5][6]. Micro-array panels for BSI investigation have been recently developed to identify various Gram-positive, Gram-negative and antibiotic resistance targets in blood cultures [5,[7][8][9].…”

Nanomedicine concepts in the general medical curriculum: initiating a discussion

“…Several clinically approved nanomedicines and nanoformulations have made the transition from bench to bedside, 34 including, for example, Verigene ® , a nanodiagnostic platform for the rapid identification of a range of infectious pathogens. [35][36][37][38] In Europe, numerous examples may be noted of commercially available nanotherapeutic products for oral and parenteral administration, respectively.…”

In vitro diagnosis of sepsis: a review

“…For example, a major strength of BC-GP is the ability to differentiate several species of Staphylococcus, as well as the mecA gene. 82,85 Verigene ® is limited to identifying certain species of fungi and Gramnegative bacteria. 83 Another weakness is the lack of published cost-effectiveness analyses.…”

“…83 Another weakness is the lack of published cost-effectiveness analyses. 85 The BC-GN and BC-GP are reliable, accurate, and rapid assays, which can be integrated into the routine workflow of a microbiology laboratory, even if their clinical benefits should be further evaluated.…”