Evaluation of the BioFire Gastrointestinal Panel to Detect Diarrheal Pathogens in Pediatric Patients

Infectious diarrhea is a global pediatric health concern; therefore, rapid and accurate detection of enteropathogens is vital. We evaluated the BioFire® FilmArray® Gastrointestinal (GI) Panel with that of comparator laboratory tests. Stool samples of pediatric patients with diarrhea were prospectively collected and tested. As a comparator method for bacteria, culture, conventional PCR for diarrheagenic E. coli, and Allplex GI-Bacteria(I) Assay were tested. For discrepancy analysis, BD MAX Enteric Bacterial Panel was used. As a comparator method for virus, BD MAX Enteric Virus Panel and immunochromatography was used and Allplex GI-Virus Assay was used for discrepancy analysis. The “true positive” was defined as culture-positive and/or positive results from more than two molecular tests. Of the 184 stool samples tested, 93 (50.5%) were true positive for 128 pathogens, and 31 (16.9%) were positive for multiple pathogens. The BioFire GI Panel detected 123 pathogens in 90 of samples. The BioFire GI Panel demonstrated a sensitivity of 100% for 12 targets and a specificity of >95% for 16 targets. The overall positive rate and multiple pathogen rate among patients in the group without underlying diseases were significantly higher than those in the group with hematologic disease (57.0% vs. 28.6% (p = 0.001) and 20.4% vs. 4.8% (p = 0.02), respectively). The BioFire GI Panel provides comprehensive results within 2 h and may be useful for the rapid identification of enteropathogens.

Comparison of the Amplisure HBV Quantitative Kit with the Qiagen Artus HBV QS-RGQ Assay for Quantifying Viral DNA in Plasma Samples of Monitoring Cases

<b><i>Background:</i></b> Monitoring of hepatitis B virus (HBV) viral load has become an essential phase in the treatment of HBV. There are many commercial assays available for HBV viral load quantification. In this study, we have evaluated the performance characteristics of Amplisure® HBV Kit in comparison with the Qiagen artus HBV QS-RGQ kit for HBV DNA quantitation. <b><i>Methods:</i></b> Comparison of 2 methods was carried out on 200 clinical samples, 150 HBV DNA positive and 50 HBV DNA negative, by a reference method. Results obtained with Amplisure® HBV Kit (Amplisure HBV) were compared using the Qiagen artus HBV QS-RGQ assay results as the comparator method. <b><i>Result:</i></b> The overall performance of the Amplisure HBV compared with the comparator method shows positive and negative clinical agreement of 100 and 76%, respectively. Among the 12 qualitative discrepant samples, all positive with Amplisure HBV were sequenced and 10 were below comparator method’s LOD. For 5 weak positives (−0.22 to 0.98 log IU/mL), the sequencing failed. The 7 other positives (0.48 to 1.89 log IU/mL) were confirmed positive by sequencing. Quantitative comparison gave an <i>r</i>² of 0.967 with a mean log difference of 0.09 log₁₀ IU/mL. <b><i>Conclusion:</i></b> This study shows that Amplisure® HBV Quantitative Kit shows comparable performance with artus HBV QS-RGQ assays and can be useful in management and therapeutic monitoring of HBV in a clinical practice.

Do We Need the Replacement of YSI 2300? A View from the Clinical Laboratory

In this issue of Journal of Diabetes Science and Technology, Baumstark et al. evaluated the analytical performance of a bench-top laboratory glucose analyzer (SUPER-GL) intended for replacement for the YSI2300-STAT analyzer, that served for several decades as a comparator method in clinical and analytical studies of blood glucose monitoring systems (BGMS). The authors concluded that the SUPER-GL’s overall performance is comparable to that of YSI2300-STAT, and has the potential to be a candidate comparator analyzer. However, the question is if we need to recommend as a “comparator method,” a specific device, that measure glucose using the same analytical method with most BGMS. In this analysis we present our point of view hoping to generate a discussion on the necessity for such a replacement.

A Novel Host-protein Assay Accurately Distinguishes Bacterial From Viral Upper Respiratory Tract Infections

Background Bacterial and viral infections are often clinically indistinguishable, particularly in upper respiratory tract infections (URTI), which leads to antibiotic misuse. A novel assay (ImmunoXpert™) that integrates measurements of three host-response proteins (TRAIL, IP-10, CRP) was recently developed to assist in differentiation between bacterial and viral etiologies. We evaluated the assay performance in URTI patients and compared it with standard laboratory measures. Methods We performed a sub-analysis of 464 patients with clinical suspicion of URTI enrolled in three previously conducted multi-center clinical studies that evaluated the assay performance in patients with acute infections: ‘Curiosity’ study (NCT01917461), ‘Opportunity’ study (NCT01931254), and ‘Pathfinder’ study (NCT01911143). Comparator method was predetermined criteria combined with expert panel adjudication, which was blinded to the test results. Diagnostic performance was evaluated by comparing test and comparator method outcomes. Results A unanimous panel adjudication was attained for 61 bacterial (13%) and 241 viral (52%) patients (162 patients (35%) had an indeterminate diagnosis). The assay distinguished between bacterial and viral infected patients with a sensitivity of 92% (95% CI: 82%- 98%) and specificity of 93% (88%-96%) with 11% equivocal test results. Overall the assay outperformed other routine laboratory tests (FIG 1), including: white blood cell count (WBC; cutoff 15,000 cells/µL, sensitivity 48% (35%-60%), P &lt; 10-−6; specificity 85% (80%-90%), P &lt; 0.05); CRP (cutoff 40 mg/L, sensitivity 82% (72%–92%), P = 0.16, specificity 79% (74%–84%), P &lt; 10-4); Procalcitonin (PCT; cutoff 0.5 ng/mL, sensitivity 22% (11%–32%), P &lt; 10–14, specificity 80% (74%–85%), P &lt; 0.001); absolute neutrophil count (ANC; cutoff 10,000 cells/µL, sensitivity 58% (45%–71%), P &lt; 10-−4, specificity 94% (91%–97%), P = 0.7). Conclusion The novel assay demonstrated superior performance compared with routine laboratory tests (WBC, ANC) and biomarkers (CRP, PCT), in distinguishing bacterial from viral etiologies in patients with URTI. It has the potential to help clinicians avoid missing bacterial infections or prescribing unwarranted antibiotics for viral URTIs. Disclosures K. Oved, MeMed Diagnostics: Board Member, Employee and Shareholder, Salary E. Eden, MeMed Diagnostics: Board Member, Employee and Shareholder, Salary T. Gottlieb, MeMed Diagnostics: Employee, Salary R. Navon, MeMed Diagnostics: Employee, Salary A. Cohen, MeMed Diagnostics: Employee, Salary O. Boico, MeMed Diagnostics: Employee, Salary M. Paz, MeMed Diagnostics: Employee, Salary L. Etshtein, MeMed Diagnostics: Employee, Salary G. Kronenfeld, MeMed Diagnostics: Employee, Salary T. Friedman, MeMed Diagnostics: Employee, Salary E. Bamberger, MeMed Diagnostics: Employee, Salary I. Chistyakov, MeMed Diagnostics: Consultant, Consulting fee I. Potasman, MeMed Diagnostics: Holding stock options, stock options

Optimal conditions for the numerical calculation of the largest Lyapunov exponent for systems of ordinary differential equations

A general indicator of the presence of chaos in a dynamical system is the largest Lyapunov exponent (LLE). This quantity provides a measure of the mean exponential rate of divergence of nearby orbits. In this paper, we show that the so-called two-particle method introduced by Benettin et al. could lead to spurious estimations of the LLE. As a comparator method, the maximum Lyapunov exponent is computed from the solution of the variational equations of the system. We show that the incorrect estimation of the LLE is based on the setting of the renormalization time and the initial distance between trajectories. Unlike previously published works, we here present three criteria that could help to determine correctly these parameters so that the LLE is close to the expected value. The results have been tested with four well known dynamical systems: Ueda, Duffing, Rössler and Lorenz.