scholarly journals Multicenter Diagnostic Accuracy Evaluation of the Luminex Aries Real-Time PCR Assay for Group B Streptococcus Detection in Lim Broth-Enriched Samples

2018 ◽  
Vol 56 (8) ◽  
Author(s):  
D. R. Hernandez ◽  
D. M. Wolk ◽  
K. L. Walker ◽  
S. Young ◽  
R. Dunn ◽  
...  
Keyword(s):  
Clinical Performance ◽  
Enrichment Culture ◽  
Culture Method ◽  
Nucleic Acid Amplification ◽  
Accuracy Evaluation ◽  
Culture Methods ◽  
Assay Sensitivity ◽  
Content Type ◽  
Group B ◽  
Positive Agreement

ABSTRACT The vertical transmission of group B Streptococcus (GBS) strains causing neonatal sepsis is one of the leading reasons for neonatal mortality worldwide. The gold standard for GBS detection is enriched culture with or without the aid of chromogenic agars. Given the high risk for morbidity and mortality in this population, high assay sensitivity is required to prevent the personal and economic costs of GBS disease. Nucleic acid amplification tests (NAATs) allow for objective determination of GBS colonization with a sensitivity and a specificity higher than those of traditional culture methods. In this study, we determined the analytical and clinical performance of the Aries GBS assay compared to those of the enrichment culture method, biochemical identification, and the NAATs used at the study sites. Remnant Lim broth samples were used to perform the Aries assay and reference testing. Upon first testing using enriched culture as the reference standard, the Aries GBS assay identified GBS with a 96.1% sensitivity (95% confidence interval [CI], 91.2 to 98.7%) and a 91.4% specificity (95% CI, 88.8 to 93.6%). The test performed with 100% positive agreement (95% CI, 83.2 to 100%) compared to the results of the BD Max GBS assay and 98.0% positive agreement (95% CI, 89.2 to 99.9%) compared to the results of the Cepheid Xpert GBS LB test. Repeatability and reproducibility were maintained in intra- and interlaboratory testing, regardless of the instrument, module, or user who performed the test. The Aries GBS assay can be set up in less than 5 min and produces results in 2 h. The easy setup, with minimal hands-on time, and high assay sensitivity and specificity make this a useful testing option for GBS screening in prepartum women.

scholarly journals Comparison of Three Nucleic Acid Amplification Tests and Culture for Detection of Group BStreptococcusfrom Enrichment Broth

2019 ◽  
Vol 57 (6) ◽  
Author(s):  
Ji H. Shin ◽  
David T. Pride
Keyword(s):  
Nucleic Acid ◽  
Standard Of Care ◽  
Culture Method ◽  
Nucleic Acid Amplification ◽  
Culture Methods ◽  
Content Type ◽  
Nucleic Acid Amplification Tests ◽  
Hands On ◽  
Group B ◽  
Care Culture

ABSTRACTColonization of the gastrointestinal and genitourinary tracts of pregnant women with group BStreptococcus(GBS) can result in vertical transmission to neonates during labor/delivery. GBS infections in neonates can cause severe complications, such as sepsis, meningitis, and pneumonia. Accurate detection is critical because administration of intrapartum antibiotics can significantly reduce transmission. We compared the clinical sensitivities of three nucleic acid amplification tests (NAATs), the Hologic Panther Fusion GBS, Luminex Aries GBS, and Cepheid Xpert GBS LB assays, to that of the standard of care culture method recommended for GBS screening using 500 vaginal-rectal swab specimens after 18 to 24 h of broth enrichment. We identified 108 positive specimens (21.6%) by culture, while at least 1 of the 3 NAATs was positive for GBS in 155 specimens (31.0%). All 108 specimens positive by culture were also detected by the Panther Fusion assay, while 107/108 (99.1%) were detected by the Cepheid Xpert and Luminex Aries assays. Of the 61 specimens positive by at least 1 NAAT but negative by culture, 24 (39.3%) were positive by all 3 NAATs, suggesting that they represent true positives (TPs). NAATs offer less hands-on time, greater throughput, faster time to result, and potentially greater sensitivity than culture methods, and they should be considered the new gold standard for intrapartum GBS screening.

scholarly journals Comparison of the Panther Fusion and BD MAX Group B Streptococcus (GBS) Assays for Detection of GBS in Prenatal Screening Specimens

2019 ◽  
Vol 57 (11) ◽  
Author(s):  
Gregory J. Berry ◽  
Fan Zhang ◽  
Ryhana Manji ◽  
Stefan Juretschko
Keyword(s):  
Late Onset ◽  
Clinical Performance ◽  
Group B Streptococcus ◽  
Turnaround Time ◽  
Nucleic Acid Amplification ◽  
Kappa Statistics ◽  
Loading Capacity ◽  
Content Type ◽  
Return Visits ◽  
Group B

ABSTRACT Streptococcus agalactiae or group B Streptococcus (GBS) is the cause of early- and late-onset GBS disease in neonates and can present as septicemia, meningitis, and pneumonia. Our objective was to compare the performance of two FDA-approved nucleic acid amplification tests (NAATs), the Panther Fusion and BD MAX systems, for detection of GBS in vaginal-rectal screening specimens. A total of 510 vaginal-rectal prepartum specimens were tested simultaneously in both NAATs following broth enrichment. Assay agreement was calculated using kappa statistics. Overall agreement between assays was 99.0% (505/510; 95% confidence interval, 0.951 to 0.997; kappa = 0.974). Discordant results were retested with both assays and by standard culture. The assays were also compared for workflow characteristics, including time to first results (TFR), total turnaround time (TAT), number of return visits to load additional specimens, and hands-on time (HoT). Using a standard run size of 60 specimens/day, the Panther Fusion assay had a longer TFR (2.4 versus 2.0 h) but showed a shorter overall TAT for all 60 samples (3.98 versus 7.18 h) due to an increased initial sample loading capacity, and it required less labor (35.0 versus 71.3 s/sample) and fewer return visits for loading additional specimens (0 versus 2). The Panther Fusion system also had a larger sample loading capacity (120 versus 24 samples) and greater 8-h throughput (335 versus 96 samples). In summary, the Panther Fusion GBS assay has clinical performance comparable to that of the BD MAX GBS assay but provides a faster TAT, less HoT, and higher throughput.

scholarly journals Multicenter Evaluation of NeuMoDx Group B Streptococcus Assay on the NeuMoDx 288 Molecular System

2018 ◽  
Vol 57 (2) ◽  
Author(s):  
C. L. Emery ◽  
R. F. Relich ◽  
T. H. Davis ◽  
S. A. Young ◽  
M. D. Sims ◽  
...  
Keyword(s):  
Enrichment Culture ◽  
Molecular System ◽  
Group B Streptococcus ◽  
Reference Method ◽  
Culture Method ◽  
Developed Countries ◽  
Nucleic Acid Amplification ◽  
Gold Standard Reference ◽  
Control And Prevention ◽  
Group B

ABSTRACT Group B Streptococcus (GBS) is the leading cause of neonatal sepsis and meningitis in developed countries. Recommendations for antepartum GBS detection include enriched culture with several options for identifying GBS, some of which are time-consuming. To reduce the time for identification and determination of the maternal GBS colonization status, rapid nucleic acid amplification technologies have been developed and commercialized. For rapid detection of GBS, a three-site clinical study was conducted to evaluate the NeuMoDx GBS assay, a real-time PCR test performed for vaginal/rectal swab specimens in Lim broth enrichment culture on the NeuMoDx 288 molecular system (NeuMoDx system); these data were used to a support 510(k) submission. A total of 1,250 eligible remnant samples were prospectively enrolled and tested during the study. The results of the PCR assay were compared to the results of the Centers for Disease Control and Prevention (CDC)-recommended enriched-culture method, which served as the gold standard reference method for the study. The NeuMoDx GBS assay results yielded a sensitivity of 96.9% (95% confidence interval [CI] = 94.1 to 98.4), specificity of 96.0% (95% CI = 94.6 to 97.1), and a total agreement with the reference method of 96.2% (95% CI = 93.8 to 98.3). NeuMoDx GBS assay results were also compared to results obtained using the BD MAX GBS assay on the BD MAX system. The two systems demonstrated a total percent agreement of 98.0% (95% CI = 95.5 to 100.0). The performance of the NeuMoDx GBS assay implemented on the NeuMoDx system compared favorably to the CDC enriched-culture method and to the BD MAX GBS assay.

scholarly journals Evaluation of the cobas Cdiff Test for Detection of Toxigenic Clostridium difficile in Stool Samples

2017 ◽  
Vol 55 (12) ◽  
pp. 3426-3436 ◽  
Author(s):  
Lance R. Peterson ◽  
Stephen A. Young ◽  
Thomas E. Davis ◽  
Zi-Xuam Wang ◽  
John Duncan ◽  
...  
Keyword(s):  
Clostridium Difficile ◽  
False Negative ◽  
Reference Method ◽  
Culture Method ◽  
Nucleic Acid Amplification ◽  
Culture Methods ◽  
Content Type ◽  
Toxigenic Culture ◽  
Discrepancy Analysis ◽  
Stool Samples

ABSTRACTNucleic acid amplification tests (NAATs) are reliable tools for the detection of toxigenicClostridium difficilefrom unformed (liquid or soft) stool samples. The objective of this study was to evaluate performance of the cobas Cdiff test on the cobas 4800 system using prospectively collected stool specimens from patients suspected of havingC. difficileinfection (CDI). The performance of the cobas Cdiff test was compared to the results of combined direct and broth-enriched toxigenic culture methods in a large, multicenter clinical trial. Additional discrepancy analysis was performed by using the XpertC. difficileEpi test. Sample storage was evaluated by using contrived and fresh samples before and after storage at −20°C. Testing was performed on samples from 683 subjects (306 males and 377 females); 113 (16.5%) of 683 subjects were positive for toxigenicC. difficileby direct toxigenic culture, and 141 of 682 subjects were positive by using the combined direct and enriched toxigenic culture method (reference method), for a prevalence rate of 20.7%. The sensitivity and specificity of the cobas Cdiff test compared to the combined direct and enriched culture method were 92.9% (131/141; 95% confidence interval [CI], 87.4% to 96.1%) and 98.7% (534/541; 95% CI, 97.4% to 99.4%), respectively. Discrepancy analysis using results for retested samples from a second NAAT (Xpert C. difficile/Epi test; Cepheid, Sunnyvale, CA) found no false-negative and 4 false-positive cobas Cdiff test results. There was no difference in positive and negative results in comparisons of fresh and stored samples. These results support the use of the cobas Cdiff test as a robust aid in the diagnosis of CDI.

scholarly journals Evaluation of StrepBSelectChromogenic Medium and the Fast-Track Diagnostics Group B Streptococcus (GBS) Real-Time PCR Assay Compared to Routine Culture for Detection of GBS during Antepartum Screening

2017 ◽  
Vol 55 (7) ◽  
pp. 2137-2142 ◽  
Author(s):  
Deirdre L. Church ◽  
Heather Baxter ◽  
Tracie Lloyd ◽  
Oscar Larios ◽  
Daniel B. Gregson
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Fast Track ◽  
Group B Streptococcus ◽  
Culture Method ◽  
Predictive Values ◽  
Content Type ◽  
Standard Culture ◽  
Group B ◽  
The Cost

ABSTRACTLife-threatening infection in neonates due to group BStreptococcus(GBS) is preventable by screening of near-term pregnant women and treatment at delivery. A total of 295 vaginal-rectal swabs were collected from women attending antepartum clinics in Calgary, Alberta, Canada. GBS colonization was detected by the standard culture method (Strep B Carrot Broth subcultured to blood agar with a neomycin disk) and compared to recovery with Strep Group B Broth (Dalynn Biologicals) subcultured to StrepBSelectchromogenic medium (CM; Bio-Rad Laboratories) and the Fast-Track Diagnostics GBS real-time PCR (quantitative PCR [qPCR]) assay (Phoenix Airmid Biomedical Corp.) performed with broth-enriched samples and the Abbottm2000sp/m2000rt system. A total of 62/295 (21%) women were colonized with GBS; 58 (19.7%) cases were detected by standard culture, while CM and qPCR each found 61 (20.7%) cases. The qPCR and CM were similar in performance, with sensitivities, specificities, and positive and negative predictive values of 98.4 and 98.4%, 99.6 and 99.6%, 98.4 and 98.4%, and 99.6 and 99.6%, respectively, compared to routine culture. Both qPCR and CM would allow more rapid reporting of routine GBS screening results than standard culture. Although the cost per test was similar for standard culture and CM, the routine use of qPCR would cost approximately four times as much as culture-based detection. Laboratories worldwide should consider implementing one of the newer methods for primary GBS testing, depending on the cost limitations of different health care jurisdictions.

scholarly journals Comparing the Yield of Staphylococcus aureus Recovery with Static versus Agitated Broth Incubation

2018 ◽  
Vol 2018 ◽  
pp. 1-3
Author(s):  
Carol E. Muenks ◽  
Patrick G. Hogan ◽  
Carey-Ann D. Burnham ◽  
Stephanie A. Fritz
Keyword(s):  
Staphylococcus Aureus ◽  
Enrichment Culture ◽  
Culture Method ◽  
Ambient Air ◽  
Built Environments ◽  
Culture Methods ◽  
Semiquantitative Assessment ◽  
Direct Plating ◽  
Static Conditions ◽  
Broth Enrichment

Given the lack of standardization of methodologies for microbial recovery from built environments, we sought to compare the yield of Staphylococcus aureus with a broth enrichment method when incubated in agitated versus static conditions. Five unique strains of S. aureus at five different concentrations were cultured to compare direct plating, agitated broth enrichment, and static broth enrichment culture methods. All samples were incubated at 35° in ambient air. The lowest concentration recovered across three replicates and five strains did not differ between culture methods (Fisher’s exact test, p=0.50); notably, recovery of S. aureus was equivalent between static and agitated broth incubation. When broth enrichment was used (both static and agitated), the burden of S. aureus growth was higher (by semiquantitative assessment of 4-quadrant streaking) compared to the direct plating culture method. Optimizing strategies for microbial recovery is essential, particularly in areas of lower biomass, given the paucity of research concerning microbial communities of built environments. The results of this study, in conjunction with other experiments investigating microbiomes of built environments, can help inform protocols for standardizing culturing methods within built environments.

scholarly journals Increased Clinical Specificity with Ultrasensitive Detection of Clostridioides difficile Toxins: Reduction of Overdiagnosis Compared to Nucleic Acid Amplification Tests

2019 ◽  
Vol 57 (11) ◽  
Author(s):  
Johanna Sandlund ◽  
Joel Estis ◽  
Phoebe Katzenbach ◽  
Niamh Nolan ◽  
Kirstie Hinson ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Patient Outcomes ◽  
Single Molecule ◽  
Clinical Performance ◽  
Neutralization Assay ◽  
Nucleic Acid Amplification ◽  
Content Type ◽  
Clostridioides Difficile ◽  
Health Care Associated Infections ◽  
Stool Specimens

ABSTRACT Clostridioides difficile infection (CDI) is one of the most common health care-associated infections, resulting in significant morbidity, mortality, and economic burden. Diagnosis of CDI relies on the assessment of clinical presentation and laboratory tests. We evaluated the clinical performance of ultrasensitive single-molecule counting technology for detection of C. difficile toxins A and B. Stool specimens from 298 patients with suspected CDI were tested with the nucleic acid amplification test (NAAT; BD MAX Cdiff assay or Xpert C. difficile assay) and Singulex Clarity C. diff toxins A/B assay. Specimens with discordant results were tested with the cell cytotoxicity neutralization assay (CCNA), and the results were correlated with disease severity and outcome. There were 64 NAAT-positive and 234 NAAT-negative samples. Of the 32 NAAT+/Clarity− and 4 NAAT−/Clarity+ samples, there were 26 CCNA− and 4 CCNA− samples, respectively. CDI relapse was more common in NAAT+/toxin+ patients than in NAAT+/toxin− and NAAT−/toxin− patients. The clinical specificity of Clarity and NAAT was 97.4% and 89.0%, respectively, and overdiagnosis was more than three times more common in NAAT+/toxin− than in NAAT+/toxin+ patients. The Clarity assay was superior to NAATs for the diagnosis of CDI, by reducing overdiagnosis and thereby increasing clinical specificity, and the presence of toxins was associated with negative patient outcomes.

scholarly journals Design and Validation of Transcription-Mediated-Amplification Nucleic Acid Amplification Tests forMycoplasma genitalium

2019 ◽  
Vol 57 (8) ◽  
Author(s):  
Brett Kirkconnell ◽  
Barbara Weinbaum ◽  
Katherine Santos ◽  
Trisha Le Nguyen ◽  
Bryan Vinluan ◽  
...  
Keyword(s):  
Clinical Performance ◽  
Mycoplasma Genitalium ◽  
Vaginal Swab ◽  
Nucleic Acid Amplification ◽  
Clinical Validation ◽  
Analytical Sensitivity ◽  
Reference Standard ◽  
Content Type ◽  
Sensitivity Specificity

ABSTRACTMycoplasma genitaliumis a sexually transmitted bacterium linked to adverse sexual and reproductive health outcomes in women and men.M. genitaliumis difficult to culture, and in the absence of validated amplified molecular methods for diagnosis of infection, there is no reference standard available for use as a comparator for the validation of newM. genitaliumdiagnostic tests. We evaluated the analytical and clinical performance of three transcription-mediated amplification (TMA) tests forM. genitalium, each targeting unique rRNA sequences, for use as a composite comparator for clinical validation of the AptimaMycoplasma genitalium(AMG) assay, anin vitrodiagnostic (IVD) TMA test that targets 16 s rRNA ofM. genitalium. Analytical sensitivity, specificity, and strain inclusivity of all four TMA tests were determined using nine laboratory strains ofM. genitaliumand 56 nontarget bacteria, protozoa, and viruses. Analytical sensitivity of the tests forM. genitaliumranged from 0.017 to 0.040 genome equivalents/ml. None of the nontarget organisms evaluated cross-reacted with any test. A composite comparator reference standard consisting of the 3 alternate (Alt) TMA tests was used to evaluate the clinical performance of the AMG assay by testing residual vaginal swab, female urine, and male urine specimens obtained from 1,400 adult subjects from three U.S. clinical sites. Using this reference standard to establish infected specimen status, the sensitivity, specificity, and overall agreement of the AMG IVD assay were 100%, 99.9%, and 99.9%, respectively. These results demonstrate the utility of molecular composite reference standard methodology for the clinical validation of future IVD tests for this organism.

scholarly journals Probing the dissonance among the diagnostic outputs of multiple approaches used for detection of Methicillin-resistant Staphylococcus aureus (MRSA)

2020 ◽  
Author(s):  
Ujjwal Ranjan Dahiya ◽  
Arnab Sikidar ◽  
Priyanka Sharma ◽  
Chitra Rawat ◽  
Benu Dhawan ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Culture Method ◽  
Nucleic Acid Amplification ◽  
Detection Methods ◽  
Diagnostic Efficiency ◽  
Coagulase Negative Staphylococci ◽  
Culture Methods ◽  
Methicillin Resistant ◽  
Conventional Culture

Methicillin-resistant staphylococcus aureus (MRSA) is an extremely infectious hospital acquired bacterial pathogen often found in post-surgical patients globally. Early detection of such pathogens is a critical requirement to eliminate or reduce the incidence of antimicrobial resistance as well as for effective management of the disease. Despite the development of multiple biochemical, microbiological and nucleic acid amplification techniques (NAATs), conventional culture methods are widely used clinically owing to high variability between the methods, technical skills, and infrastructural needs. Further, multiple reports suggest a significant variation among diagnostic output for MRSA detection. This work attempts to probe the discordance among the diagnostic output of three commonly used methods while trying to understand the underlying cause of variability. MRSA detection on 217 clinical pus isolates was carried out using three different methods namely, conventional culture method, qPCR-based amplification, and a modern LAMP-based detection approach. Also, to confirm the presence of MRSA and distinguish from coagulase-negative staphylococci (CoNS), as well as to investigate the observed differences between qPCR and LAMP outputs, melt curve analysis was performed on discordant samples. LAMP-based MRSA detection was found to be the optimum method. In summary, this study evaluates the diagnostic efficiency of the different detection methods, while probing for possible explanations for the observed differences.

Validation of the ANSR®Listeria Method for Detection of Listeria spp. in Selected Foods

2015 ◽  
Vol 98 (5) ◽  
pp. 1290-1300 ◽  
Author(s):  
Oscar Caballero ◽  
Susan Alles ◽  
Michael Wendorf ◽  
R Lucas Gray ◽  
Kayla Walton ◽  
...  
Keyword(s):  
Culture Method ◽  
Cross Reactivity ◽  
Single Step ◽  
Probability Of Detection ◽  
Nucleic Acid Amplification ◽  
Culture Methods ◽  
Detection Model ◽  
Smoked Salmon ◽  
Standard Culture ◽  
Nicking Enzyme

Abstract ANSR®Listeria was previously certified as Performance Tested MethodSM 101202 for detection of Listeria spp. on selected environmental surfaces. This study proposes a matrix extension to the method for detection of Listeria spp. in selected food matrixes. The method is an isothermal nucleic acid amplification assay based on the nicking enzyme amplification reaction technology. Following single-step sample enrichment for 16–24 h, the assay is completed in less than 50 min, requiring only simple instrumentation. Inclusivity testing was performed using a panel of 51 strains of Listeria spp., representing the species L. grayi, L. innocua, L. ivanovii, L. monocytogenes, L. seeligeri, and L. welshimeri. All strains tested were detected by the ANSR assay. Exclusivity testing of 30 strains representing non-Listeria Gram-positive bacteria yielded no evidence of cross-reactivity. Performance of the ANSR method for detection of Listeria spp. was compared to that of reference culture procedures for pasteurized liquid egg, pasteurized 2% milk, Mexican-style cheese, ice cream, smoked salmon, lettuce, cantaloupe, and guacamole. Data obtained in these unpaired studies and analyzed using a probability of detection model demonstrated that there were no statistically significant differences in results between the ANSR and reference culture methods, except for milk at 16 h and cantaloupe. In milk and smoked salmon, ANSR sensitivity was low at 16 h and therefore the recommended incubation time is 24 h. In cantaloupe, ANSR was found to be more sensitive than the reference culture method at both 16 and 24 h in independent aboratory testing. The ANSR Listeria method can be used as an accurate, rapid, and simple alternative to standard culture methods for detection of Listeria spp. in selected food types.

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