scholarly journals Identification of Gram-Negative Bacteria and Genetic Resistance Determinants from Positive Blood Culture Broths by Use of the Verigene Gram-Negative Blood Culture Multiplex Microarray-Based Molecular Assay

2015 ◽  
Vol 53 (8) ◽  
pp. 2460-2472 ◽  
Author(s):  
Nathan A. Ledeboer ◽  
Bert K. Lopansri ◽  
Neelam Dhiman ◽  
Robert Cavagnolo ◽  
Karen C. Carroll ◽  
...  
Keyword(s):  
Blood Culture ◽  
Positive Blood Culture ◽  
Klebsiella Oxytoca ◽  
Genetic Resistance ◽  
Reference Method ◽  
Negative Blood Culture ◽  
Gram Negative ◽  
Content Type ◽  
Resistance Determinants ◽  
Percent Agreement

Bloodstream infection is a serious condition associated with significant morbidity and mortality. The outcome of these infections can be positively affected by the early implementation of effective antibiotic therapy based on the identification of the infecting organism and genetic markers associated with antibiotic resistance. In this study, we evaluated the microarray-based Verigene Gram-negative blood culture (BC-GN) assay in the identification of 8 genus or species targets and 6 genetic resistance determinants in positive blood culture broths. A total of 1,847 blood cultures containing Gram-negative organisms were tested using the BC-GN assay. This comprised 729 prospective fresh, 781 prospective or retrospective frozen, and 337 simulated cultures representing 7 types of aerobic culture media. The results were compared to those with standard bacterial culture and biochemical identification with nucleic acid sequence confirmation of the resistance determinants. Among monomicrobial cultures, the positive percent agreement (PPA) of the BC-GN assay with the reference method was as follows; Escherichia coli , 100%; Klebsiella pneumoniae , 92.9%; Klebsiella oxytoca , 95.5%; Enterobacter spp., 99.3%; Pseudomonas aeruginosa , 98.9%; Proteus spp., 100%; Acinetobacter spp., 98.4%; and Citrobacter spp., 100%. All organism identification targets demonstrated >99.5% negative percent agreement (NPA) with the reference method. Of note, 25/26 cultures containing K. pneumoniae that were reported as not detected by the BC-GN assay were subsequently identified as Klebsiella variicola . The PPA for identification of resistance determinants was as follows; bla CTX-M , 98.9%; bla KPC , 100%; bla NDM , 96.2%; bla OXA , 94.3%; bla VIM , 100%; and bla IMP , 100%. All resistance determinant targets demonstrated >99.9% NPA. Among polymicrobial specimens, the BC-GN assay correctly identified at least one organism in 95.4% of the broths and correctly identified all organisms present in 54.5% of the broths. The sample-to-result processing and automated reading of the detection microarray results enables results within 2 h of culture positivity.

scholarly journals Clinical Performance of the Novel GenMark Dx ePlex Blood Culture ID Gram-Positive Panel

2020 ◽  
Vol 58 (4) ◽  
Author(s):  
Karen C. Carroll ◽  
Jennifer L. Reid ◽  
Adam Thornberg ◽  
Natalie N. Whitfield ◽  
Deirdre Trainor ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Blood Culture ◽  
Resistance Genes ◽  
Positive Blood Culture ◽  
The United States ◽  
Gram Positive ◽  
Gram Negative ◽  
Content Type ◽  
Percent Agreement ◽  
Antimicrobial Resistance Genes

ABSTRACT Rapid identification from positive blood cultures is standard of care (SOC) in many clinical microbiology laboratories. The GenMark Dx ePlex Blood Culture Identification Gram-Positive (BCID-GP) Panel is a multiplex nucleic acid amplification assay based on competitive DNA hybridization and electrochemical detection using eSensor technology. This multicenter study compared the investigational-use-only (IUO) BCID-GP Panel to other methods of identification of 20 Gram-positive bacteria, four antimicrobial resistance genes, and both Pan Candida and Pan Gram-Negative targets that are unique to the BCID-GP Panel. Ten microbiology laboratories throughout the United States collected residual, deidentified positive blood culture samples for analysis. Five laboratories tested both clinical and contrived samples with the BCID-GP Panel. Comparator identification methods included each laboratory’s SOC, which included matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) and automated identification systems as well as targeted PCR/analytically validated real-time PCR (qPCR) with bidirectional sequencing. A total of 2,342 evaluable samples (1,777 clinical and 565 contrived) were tested with the BCID-GP Panel. The overall sample accuracy for on-panel organisms was 89% before resolution of discordant results. For pathogenic Gram-positive targets (Bacillus cereus group, Enterococcus spp., Enterococcus faecalis, Enterococcus faecium, Staphylococcus spp., Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus lugdunensis, Listeria spp., Listeria monocytogenes, Streptococcus spp., Streptococcus agalactiae, Streptococcus anginosus group, Streptococcus pneumoniae, and Streptococcus pyogenes), positive percent agreement (PPA) and negative percent agreement (NPA) ranged from 93.1% to 100% and 98.8% to 100%, respectively. For contamination rule-out targets (Bacillus subtilis group, Corynebacterium, Cutibacterium acnes, Lactobacillus, and Micrococcus), PPA and NPA ranged from 84.5% to 100% and 99.9% to 100%, respectively. Positive percent agreement and NPA for the Pan Candida and Pan Gram-Negative targets were 92.4% and 95.7% for the former and 99.9% and 99.6% for the latter. The PPAs for resistance markers were as follows: mecA, 97.2%; mecC, 100%; vanA, 96.8%; and vanB, 100%. Negative percent agreement ranged from 96.6% to 100%. In conclusion, the ePlex BCID-GP Panel compares favorably to SOC and targeted molecular methods for the identification of 20 Gram-positive pathogens and four antimicrobial resistance genes in positive blood culture bottles. This panel detects a broad range of pathogens and mixed infections with yeast and Gram-negative organisms from the same positive blood culture bottle.

scholarly journals Preliminary Evaluation of the Research-Use-Only (RUO) iCubate iC-GPC Assay for Identification of Select Gram-Positive Bacteria and Their Resistance Determinants in Blood Culture Broths: TABLE 1

2015 ◽  
Vol 53 (12) ◽  
pp. 3931-3934 ◽  
Author(s):  
Blake W. Buchan ◽  
Garrett C. Reymann ◽  
Paul A. Granato ◽  
Brenda R. Alkins ◽  
Patricia Jim ◽  
...  
Keyword(s):  
Blood Culture ◽  
Staphylococcus Epidermidis ◽  
Bacterial Species ◽  
Genetic Resistance ◽  
Preliminary Evaluation ◽  
Gram Positive ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Resistance Determinants ◽  
On Demand

The iC-GPC assay (iCubate, Huntsville, AL) provides a molecular option for the rapid, on-demand analysis of positive blood cultures. A preliminary evaluation of the iC-GPC assay using 203 clinical or seeded specimens demonstrated a sensitivity of 93.8% to 100% and a specificity of 98.0% to 100% for the identification of five Gram-positive bacterial species (Staphylococcus aureus,Staphylococcus epidermidis,Streptococcus pneumoniae,Enterococcus faecalis, andEnterococcus faecium) and three associated genetic resistance determinants (mecA,vanA, andvanB) in positive blood culture broths.

Significance of Serial C-Reactive Protein Responses in Neonatal Infection and Other Disorders

PEDIATRICS ◽  
1993 ◽  
Vol 92 (3) ◽  
pp. 431-435
Author(s):  
Massroor Pourcyrous ◽  
Henrietta S. Bada ◽  
Sheldon B. Korones ◽  
Vickie Baselski ◽  
Seok P. Wong
Keyword(s):  
Blood Culture ◽  
Positive Blood Culture ◽  
Group B Streptococcus ◽  
Negative Blood Culture ◽  
C Reactive Protein ◽  
Infection Group ◽  
Gram Negative ◽  
Reactive Protein ◽  
Single Organism ◽  
Group B

Objective. This study was performed to determine prospectively whether, in the presence of proved or presumed bacterial infection, the sensitivity of serum C-reactive protein (CRP) response could be enhanced by serial rather than single determinations. We also sought to assess CRP responses to clinically identified noninfectious disorders. Design. The CRP responses of 491 infants on 691 occasions of suspected infection were assessed. CRP levels were measured initially and twice again at 12-hour intervals (rate immunonephelometry). Assessments also included a blood culture, complete blood cell count, and chest radiograph and culture of spinal fluid when appropriate. CRP responses were correlated with four designated clinical groups: (1) positive blood or cerebrospinal fluid cultures (n = 190); (2) negative blood culture-definite infection (necrotizing enterocolitis stages 2 and 3, pneumonia, subcutaneous abscess) (n = 52); (3) negative blood culture-possible infection (antenatal risk factors, meconium aspiration, positive urine group B streptococcus antigen, necrotizing enterocolitis stage 1, febrile infants) (n = 287); and (4) negative blood culture-no infection (respiratory distress syndrome, transient tachypnea of the newborn, patent ductus arteriosus, tissue trauma) (n = 160). Diagnoses were made before CRP results were known. Results. In all, 187 (27%) of the blood cultures were positive. A single organism was recovered from 174 of these; two organisms from 13. Among the single-organism cultures, 50 (29%) were Gram-negative, 120 (69%) were Gram-positive, and 4 (2%) were budding yeasts. CRP levels were elevated in various groups as follows: in the positive blood culture group (by organism), Gram-negative rods, 92% (46/50); group B streptococcus, 92% (12/13); Staphylococcus aureus, 89% (8/9); group D streptococcus, 71% (10/14); Streptococcus viridans, 60% (6/10); Staphylococcus epidermidis, 55% (40/73). In the negative blood culture-definite infection group, CRP levels were abnormal in 88%; in the negative culture-possible infection group, CRP was elevated in 33%; and in the negative blood culture-no infection group, CRP was elevated in 9%. Serial determinations of CRP resulted in enhanced sensitivity in the positive blood culture group, the negative blood culture-definite infection group, and the negative blood culture-possible infection group. Initial determinations by themselves were inadequatey sensitive. Serial determinations did not enhance sensitivity of the negative blood culture-no infection group. High specificity (91%) is suggested by the low incidence of abnormal CRP levels among infants who were not infected. Conclusions. These data suggest that it would be appropriate to conduct a cautious, controlled trial to assess the safety of discontinuing antibiotic therapy if three serial CRP measurements are normal and if there are no other clinical factors suggestive of infection. The data also indicate the necessity for serial determinations of CRP for optimal sensitivity.

scholarly journals 2174. Comparison of the Verigene® and the ePlex® Blood Culture Identification Panels for Gram-Positive and Gram-Negative Bloodstream Infections

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S738-S738
Author(s):  
J Kristie Johnson ◽  
Zegbeh Kpadeh-Rogers ◽  
Gwen Paszkiewicz ◽  
Kimberly C Claeys
Keyword(s):  
Blood Culture ◽  
Positive Blood Culture ◽  
Medical Center ◽  
Reference Method ◽  
Bloodstream Infections ◽  
Gram Positive ◽  
Gram Negative ◽  
E Coli ◽  
Culture Identification ◽  
Positive Agreement

Abstract Background Rapid diagnostic testing for the management of bloodstream infections has become paramount to improving patient outcomes. The primary objective of this study was to assess the differences between 2 FDA approved instruments. Methods Retrospective study from August 2018 to April 2019 at the University of Maryland Medical Center. One positive blood culture from each patient was tested using the Verigene® blood culture Gram-positive (BC-GP) or Gram-negative (BC-GN) panels based on the Gram stain and then analyzed using the ePlex® Blood Culture Identification (BCID) Gram-positive (BCID-GP) or Gram-negative (BCID-GN) research-use-only panels and compared with culture results. Results The study consisted of 140 positive blood culture bottles. 14 bottles were excluded for a total of 55 GN and 71 GP bottles. Of the 55 GN bottles, 3 had 2 GN rods for a total of 58 GNRs. BCID-GN missed 1 P. aeruginosa, 2 S. maltophilia, and 1 E. coli for a 93% (53/57) positive agreement. The BCID-GN does not detect A. junii and therefore it was excluded. BC-GN did not identify 1 K. pneumoniae with a 98% (47/48) positive agreement. BC-GN does not include the detection of S. maltophilia (4), Serratia (4), Morganella (1), and B. fragilis (1)and these were excluded in the BC-GN analysis. CTX-M was the only resistant marker detected and both panels identified it correctly. 5 samples using the BCID-GN also detected Pan Gram-Positive; 3 grew GP organisms, the other 2 only grew E. coli. Of the 71 GP bottles, 3 had two GP bacteria totaling 74 GPs. BCID-GP missed 1 S. aureus, 1 invalid, and called an E. faecalis that was not identified by the reference method for a 99% (72/73) positive agreement. BC-GP does not detect Micrococcus (6) or E. gallinarum (1) and missed 1 S. mitis/oralis for a 99% (66/67) positive agreement. 18 samples were positive for mecA detected by both panels. 4 samples were vanA/B positive; 1 by BCID-GP was sensitive to vancomycin and not detected by BC-GP. BCID-GP detected 1 sample as Pan Gram-negative although a GNR was not detected. Conclusion BothVerigene® and ePlex® GP and GN panels have a high percent positive agreement. Laboratories should take into consideration the epidemiology of their bloodstream infections when deciding on panels for the rapid detection of bloodstream infections. Disclosures All authors: No reported disclosures.

scholarly journals 649. Clinical Implementation of a Rapid Susceptibility Testing Procedure, Directly From a Positive Blood Culture Using the Vitek®2 System on Gram Negative Rods

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S383-S383
Author(s):  
Charma Henry ◽  
Dustin Evans ◽  
Daniel Navas ◽  
Arleen Barker ◽  
Chonnapat Somyos ◽  
...  
Keyword(s):  
Blood Culture ◽  
Positive Blood Culture ◽  
Susceptibility Testing ◽  
Testing Procedure ◽  
Turnaround Time ◽  
National Average ◽  
Major Error ◽  
Clinical Implementation ◽  
Salmonella Spp ◽  
Gram Negative

Abstract Background The national average of identification and susceptibility for organisms isolated from positive blood culture to final susceptibility based on growth on solid media is 48 hours. The goal of this research was to prove that the Vitek®2 (bioMérieux, Inc.) system can provide an accurate and reliable susceptibility result directly from positive blood culture for Gram negative rods and reduce the turnaround time (TAT) from positive blood culture to the final susceptibility. Methods An FDA-modified validation procedure was performed on positive blood cultures directly from the bottle to the VITEK®2 System for susceptibility testing. The protocol tested and validated an aliquot of 50uL of blood directly from the positive bottle into 10 mL of saline (1:200). The solution was vortexed and 3mL were placed in the VITEK®2 test tube. This protocol was intended only for Gram negative rods using the AST-GN70, AST-GN81 & AST-GN801 cards. This protocol followed the CLSI M52 and M100 guidelines. Results 515 organisms from clinical blood culture samples from July 2018 to October 2019 were evaluated. Organisms included, but were not limited to: E. coli, K. pneumoniae, Enterobacter spp., and P. aeruginosa, Proteus spp., Salmonella spp., Acinetobacter spp., and S. maltophilia. There were 5,201 drug/bug combinations. AdventHealth Orlando achieved an essential agreement of 99.32% (n=5,166), minor error 0.74% (n=39) major error 0.02% (n=1) and very major error 0.49% (n=2). A 100% agreement was achieved on detection of ESBL, CRE, and MDR organisms. Conclusion Rapid direct blood culture protocol using the VITEK®2 System and the AST-GN cards is accurate, reliable and can be performed with less than 1 minute hands-on time. The protocol can be implemented in any laboratory at no additional costs or modification where the current VITEK®2 AST-GN panels are in use. This protocol was clinically implemented at AdventHealth Orlando on July 15, 2019. Compared with the national average of 72 hours, the TAT obtained during this study was 23 hours from positive blood culture to final susceptibility, a significant reduction of 25 hours. The authors encourage bioMérieux Inc. to evaluate and explore the opportunity to expand the use of the VITEK®2 system for this application with the appropriate clinical trial. Disclosures All Authors: No reported disclosures

scholarly journals Evaluation of the Performance of Direct Susceptibility Test by VITEK-2 from Positively Flagged Blood Culture Broth for Gram-Negative Bacilli

2021 ◽  
Author(s):  
Kavipriya D. ◽  
Suman Susan Prakash ◽  
Sarumathi Dhandapani ◽  
Deepashree Rajshekar ◽  
Apurba Sankar Sastry
Keyword(s):  
Blood Culture ◽  
Susceptibility Testing ◽  
Blood Stream Infection ◽  
Tertiary Care ◽  
Reference Method ◽  
Culture Broth ◽  
Timely Initiation ◽  
Gram Negative ◽  
Mortality And Morbidity ◽  
Vitek 2

Abstract Background Timely initiation of antimicrobial therapy in patients with blood stream infection is absolutely necessary to reduce mortality and morbidity. Most clinical microbiology laboratories use conventional methods for identification and antimicrobial susceptibility testing (AST) that involve biochemical methods for identification followed by AST by disk diffusion. The aim of the current study is to assess the various errors associated with direct susceptibility testing done from blood culture broth using automated AST system-Vitek-2 compact compared with the reference method of AST done from bacterial colonies. Materials and Methods The study was conducted in a tertiary care public sector 2,200-bedded hospital in South India for a period of 6 months. The study involved positively flagged blood culture bottles that yielded single morphotype of Gram-negative organism by Gram stain. A total of 120 bacterial isolates were collected that consisted of consecutively obtained first 60 isolates of Enterobacteriaceae family (30 Escherichia coli and 30 Klebsiella pneumoniae) and consecutively obtained first 60 nonfermenters (30 Pseudomonas aeruginosa and 30 Acinetobacter baumannii). Vitek-2 AST was done from these 120 blood culture broth, following the protocol by Biomerieux, and results were obtained. Then, Vitek-2 was done from colonies (reference method) using appropriate panel for Enterobacteriaceae and nonfermenters, and results were obtained. Both the results were compared. Results Nonfermenters showed a better categorical agreement of 97.6%, as compared to Enterobacteriaceae, which showed 97%. Among Enterobacteriaceae, both E. coli and K. pneumoniae showed categorical agreement of 97% each. Conclusion The procedure of AST directly from blood culture broth represents a simple and effective technique that can reduce the turnaround time by 24 hours, which in turn benefits the clinician in appropriate utilization of antimicrobials for better patient care.

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