BD MAXTM Research Articles

A-278 Prevalence of Clostridium Difficile in Long-Term Care Facilities Using BD Max Cdiff Molecular Assay

Abstract Background Clostridium difficile (C.Diff) is a gram positive anaerobe producing Enterotoxin and Cytotoxin (toxin A and B respectively); more than half of million infection is diagnosed yearly with more than 10% of the cases are in patients over 65 years old. Residents in Long-Term Care Facilities (LTCF) are more prone to have C. Diff infection (CDI) because of their age, the frequent use of antibiotics, fragilities, co-morbidity, and living environment. Diagnosing CDI is based on clinical signs and symptoms as well as laboratory tests; however, the enzyme immunoassays are reliable, the tissue culture cytotoxicity is labor intensive. The nucleic acid amplification tests are becoming more the standard as first step in the diagnosis. The BD MAX™ System is a PCR walkaway instrument that provides the sensitivity, specificity and faster turnaround for the C. diff. Methods The BD MAX™ System is an automated in-vitro diagnostic test for the direct qualitative detection of the C. difficile toxin B gene (tcdB) in human liquid or soft stool specimens from patients suspected of having Clostridium difficile Infection (CDI). Premier Toxins A & B is an enzyme immunoassay for the direct detection of Clostridium difficile toxin A and toxin B in stool samples. We collected data from 5,267 samples were collected from resident in LTCF and were run using the EIA assay, 275 samples were ran using the BD Max molecular assay. We had 31 samples that were run using both assays. Statistical analyses were done using Analyse-it. Results Female accounted for 60% of the patients tested; the positivity rate was 13.2% for female and 17.2 for male using the EIA. The positivity rate was 19.2% for female and 30.6% for male when using the molecular assay. The agreement between the EIA and the PCR was 87% based on 31 samples that were run for both assays. Conclusions The BD Max gave the benefit of a fully automated with high sensitivity and specificity for the presence of toxin B producing C. Diff. The difference between the methods could be due to the lack of the sensitivity in the EIA and the fact that the molecular assay might be picking up colonized specimen or the beginning or end of infection. However, the ability to diagnose CDI early and prevent spreading of the disease to other patients is a huge benefit to the facilities. We have to keep in mind also that C.diff infection can be prevented with appropriate use of antibiotics and implementing antibiotic stewardship and infection control plan to prevent and stop spreading of the infection.

A-279 Performance Evaluation of the Respiratory Viral for BD MAX™ System in Geriatric Population

Abstract Background Respiratory Viral Infection is one of the most common infection in the geriatric population and cause major concern in the Long-Term Care Facilities. Influenza A and B, SARS-CoV-2, and respiratory syncytial virus (RSV) are responsible for most of the hospitalization and deaths among elderly patients. Rapid identification, treatment, and isolation are among the most important steps to fight the spreading of the infection. Methods The BD Respiratory Viral Panel for BD MAX™ System is an automated multiplexed real-time reverse transcriptase polymerase chain reaction (RT- PCR) test intended for the simultaneous, qualitative detection and differentiation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza A, influenza B, and/or respiratory syncytial virus (RSV) nucleic acid in nasopharyngeal swab (NPS) and anterior nasal swab (ANS) specimens from individuals with signs and symptoms of respiratory tract infection. The assay is targeting RNA from the nucleocapsid phosphoprotein gene (N1 and N2 regions) of the SARS-CoV-2, a conserved region of the matrix protein M1 gene for influenza A, conserved regions of the matrix protein M1 gene and HA gene for influenza B, conserved regions of the N and M genes for RSV, and the human RNase P gene. The assay was evaluated for: precision, reproducibility, accuracy, and correlation with BioGx for SARS-CoV-2, Solana (Quidel) for influenza A, influenza B and RSV; the percentage agreement for the evaluation steps was calculated. We ran 86 samples collected from patients residing in Long-Term Care Facilities. Statistical analyses were done using Analyse-it. Results The percentage agreement for precision, reproducibility, and accuracy were 100%. The patients’ correlation was 100% when compared to the existing molecular testing in the laboratory. Female patients accounted for 62.8% (54 female and 32 male); 2 patients were positive for both influenza A and RSV, and one patient was positive for both influenza A and SAR-CoV-2. Conclusions The Respiratory Viral panel for BD MAX™ System gave the benefit of a fully automated, high precision, accuracy and acceptable sensitivity assay; in addition, it offers easier collection (one swabs versus multiple swabs), faster turnaround time for four targets in less than three hours which allow for earlier isolation to prevent the spreading of the infection and initiating treatment when needed. As with every molecular assay avoiding contamination is very important to eliminated false positive results.

Evaluation of cobas® Liat® Cdiff, STANDARD™ M10 C. difficile and Xpert® C. difficile BT assays for rapid detection of toxigenic Clostridioides difficile

We evaluated the analytical performance of three commercial molecular assays for rapid detection of Clostridioides difficile toxin B in stool samples. The results were compared with results from the BD MAX™ Cdiff assay. We analyzed forty negative and thirty-two positive stool samples with three rapid assays: Roche cobas® Liat® Cdiff, SD Biosensor STANDARD™ M10 C. difficile and Cepheid Xpert® C. difficile BT. The assays demonstrated a sensitivity of 96.9 %, 96.9 % and 100.0 % and a specificity of 100 %, 97.5 % and 97.5 %, respectively. There is limited data available on the analytical performance of the newly introduced STANDARD™ M10 C. difficile assay. In this study, all three rapid assays demonstrated similarly high analytical performance and can be used for detection of toxigenic C. difficile.

Clinical Performance of the BD Respiratory Viral Panel for BD MAX™ System in Detecting SARS-CoV-2, Influenza A and B, and Respiratory Syncytial Virus

Using a nasopharyngeal (NP) or anterior nasal (NS) swab from prospectively collected or retrospective specimens, we assessed the clinical performance of the BD Respiratory Viral Panel (BD RVP) for BD MAX System against FDA-cleared or authorized comparators. Across prospective and retrospective specimens, positive percent agreement (PPA) was ≥ 98.4% for SARS-CoV-2, ≥ 96.7% for influenza (flu) A, ≥ 91.7% for respiratory syncytial virus (RSV), and 100% for flu B (retrospective only) while negative percent agreement (NPA) was ≥ 97.7% across all targets, leading to the assay FDA clearance. A head-to-head comparison of NS versus NP results with BD RVP was also performed; PPA was ≥ 90% and NPA ≥ 98.2% for SARS-CoV-2, flu A and RSV. These findings confirm that the BD MAX RVP assay performs well for detection and differentiation of the three viruses in NP and NS specimens, with strong interrater agreements for NS versus NP comparisons.

Validation of a new extraction-free real-time PCR test to detect MPOX virus

The monkeypox (Mpox) virus has raised significant concerns given its recent spread with an increasing number of confirmed cases worldwide. In this study, we evaluated the performance of a laboratory developed test (LDT) using BioGX Xfree hMPXV/OPXV reagents for the qualitative detection of non-variola Orthopoxviruses and Mpox virus DNA, in swabs from human pustular or vesicular rash specimens. Analytical and clinical testing analysis were carried out on two different platforms: the BD MAX™ System (BD Diagnostics) and the new pixl.16 Real-Time PCR Platform (BioGX), using a synthetic Mpox virus DNA (ATCC VR-3270SD) and residual clinical samples previously identified with an EUA approved Mpox real-time PCR assay. In the end, the Xfree hMPXV/OPXV LDT proved to be a sensitive, specific, and reproducible test for the detection of Mpox on both platforms evaluated with the pixl.16 having an advantage of a small footprint and providing faster TAT facilitated by an extraction-free workflow.

A-228 Performance Evaluation of the LabGenius C-CT/NG-BMX Assay for Detection of Chlamydia trachomatis and Neisseria gonorrhoeae

Abstract Background The LabGenius C-CT/NG-BMX assay (LabGenius CT/NG; BIOMEDUX, Gyeonggi-do, Republic of Korea) is a recently developed real-time polymerase chain reaction assay that can simultaneously detect sexual transmitted pathogens (Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG)) in vaginal swab specimen or urine specimen. Methods To evaluate the analytical performance, a total of 343 vaginal swab and 167 urine specimens were selected to compare the LabGenius CT/NG with the BD MAX™ CT/GC/TV (Becton, Dickinson and Company, NJ, USA). In addition, using binomial logistic regression analysis, we estimated the limit of detection which 95% (Lod95) detection rate were achieved in the LabGenius CT/NG. Results The LabGenius CT/NG showed almost perfect agreement with the BD MAX™ CT/GC/TV (κ = 0.826 for CT, κ = 0.944 for NG), and overall agreements between two assays were 91.6% for CT and 97.8% for NG, respectively. The LoD95 values using vaginal swab and urine specimens were 9.9 and 7.8 copies/uL for CT, and 7.6 and 5.1 copies/uL for NG, respectively. Conclusion In this study, LabGenius CT/NG demonstrated acceptable analytical performance compared to BD MAX™ CT/GC/TV, and this assay could be a cost-effective option for routine and follow-up test for detection of sexual transmitted pathogens.

A-363 Evaluating the Performance of Emerging STI Point of Care Assays Using Novel, Room Temperature Stable CT/NG/TV/MG Positive Swab Quality Control Materials

Abstract Background The emergence of Point of Care tests that detect Sexually Transmitted Infections (STIs) is critical for screening and diagnostic programs in low-resource settings. Point of Care tests that are designed to simultaneously detect Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), Trichomonas vaginalis (TV), and Mycoplasma genitalium (MG) promote rapid diagnosis and early treatment of the most common etiological agents causing STIs. Along with the roll-out and use of these tests, there is a growing need for complex multi-analyte quality control materials that are stable at room temperature and challenge test performance by identifying result deviations, lot-to-lot variability, and routine laboratory workflow errors. Microbix developed a whole-workflow multiplex quality control desiccated on a Copan FLOQSwab® that is stable at 2–30°C and contains inactivated whole-genome target pathogens. The objective of this study is to evaluate sample performance with multiple Point of Care diagnostic platforms that are currently in development and commercial IVD tests that are routinely used in the laboratory. Methods Microbix designed an inactivated STI whole-workflow control that contains whole-genome CT, NG, TV, MG, and human cells to satisfy sample adequacy control requirements. The formulation is desiccated on a Copan FLOQSwab® to mimic patient specimen formats and ensure sample compatibility with all assay workflows and elution buffers. Sample performance was evaluated with Cepheid Xpert® CT/NG assay, Cepheid Xpert® TV assay, Abbott Alinity m STI assay, BD MAX™ CT/GC/TV assay, Seegene Novaplex™ CT/NG/TV/MG assay, EliTechGroup STI PLUS ELITe MGB®Kit, and commercial Point of Care assays currently in development. Results The STI positive swab formulation demonstrated acceptable performance when tested with various nucleic acid amplification tests that detect CT, NG, TV, and MG targets. The formulations also behaved as useful quality management tools by highlighting design limitations for commercial Point of Care assays that are currently in development. Conclusion CT/NG/TV/MG whole-genome multiplex formulation desiccated on a Copan FLOQSwab® is an advantageous prospective quality control material that is stable at room temperature and supports the clinical use and accuracy of emerging STI assays, including the most challenging Point of Care test formats. The formulations showed acceptable performance on multiple platforms, demonstrating excellent commutability. Additionally, the dry swab format offers great practicality for monitoring assay performance in low-resource settings.

B-268 Validation of a New Real-Time PCR Test for the Detection of Mpox Virus on the BD MAXTM System

Abstract Background Enabling labs to rapidly respond to unexpected healthcare challenges is the kind of situations for which the BD MAX™ open system reagent suite is designed. Therefore, after the monkeypox outbreak in non-endemic countries on May 2022, development of a molecular assay for monkeypox detection on the BD MAXTM System was initiated. Methods VIASURE Monkeypox virus Real Time PCR Reagents for BD MAX™ System was designed for the qualitative detection of DNA from monkeypox virus in human skin lesion swabs in VTM/UTM obtained from individuals suspected of monkeypox infection. The Limit of Detection (LoD) was determined by testing a 3-fold dilution series across 5 concentrations. The lowest concentration with 100% detection was tested with an additional 20 replicates. The preliminary LoD was confirmed with a ≥95% detection with 20 replicates. Then, a fully contrived clinical evaluation was performed. Each contrived clinical specimen was prepared using a unique natural clinical specimen matrix (lesion swabs). Twenty (20) of the clinical specimens were prepared at 1-2X LoD, ten (10) were prepared at 3-5X LoD, and thirty (30) were tested as negative samples. Results The lowest detectable concentration of virus at which >95% of all replicates test positive (LoD) was 288 copies/mL. The results for the contrived clinical evaluation are shown in Table 1. 19/20 (≥95%) low positive specimens (1-2xLoD) and 20/20 (100%) moderate positive specimens (3-5x LoD) were detected demonstrating the functionality of the test. Conclusion VIASURE Monkeypox virus Real Time PCR Reagents for BD MAX™ System provides results in a short time and requires less than one minute of hands-on time per sample due to integration of fully automated extraction and thermocycling steps. An additional clinical testing of positive natural clinical specimens must be performed to complete evidence that this product is for the purpose and the population for which it is intended.

A-252 Differentiation of SARS-CoV-2, Influenza A and B, and Respiratory Syncytial Virus Using a Single Swab: A Clinical Performance Evaluation of the BD MAX System Multiplex PCR Assay

Abstract Background Some shared clinical features of SARS-CoV-2, influenza (flu), and respiratory syncytial virus (RSV) infection often pose a diagnostic challenge for clinicians. In that context, the use of molecular diagnostic systems multiplex assays, using a nasopharyngeal or nasal swab, facilitates the detection of the causing virus by differentiating between the RNA of each disease. Our study evaluated the clinical accuracy of one such multiplex PCR assay, the BD Respiratory Viral Panel for BD MAX™ System (BD MAX RVP). Methods Symptomatic patients that had a nasopharyngeal and nasal specimen prospectively collected from 6 geographical locations in the US were enrolled in the study between January and April 2022 along with nasopharyngeal swabs retrospectively collected between December 2019 and January 2022. All specimen testing was performed using the BD MAX System. Hologic® Flu A/B/RSV assay on Panther Fusion™ System was the comparator for flu A, flu B, and RSV while a composite of two out of three assays authorized under FDA Emergency Use Authorization (Roche cobas® SARS-CoV-2 on cobas® 6800 System, Hologic® Aptima® SARS-CoV-2 on Panther® System, and Quidel Lyra® SARS-CoV-2 on Applied Biosystems® 7500 Fast Dx) was used as comparator for SARS-CoV-2. Positive and negative percentage agreements (PPA and NPA, respectively) were calculated to determine performance. Reproducibility and precision assessments were also performed as part of the study. Results Tested specimens included 252 nasopharyngeal and 254 nasal swabs, prospectively collected, and 240 retrospectively acquired nasopharyngeal specimens. For prospectively collected SARS-CoV-2 nasopharyngeal specimens, PPA of 98.8% (95% CI 93.6, 99.8) and NPA of 98.2% (95% CI 94.9, 99.4) were observed while for flu A, PPA was 100% (95% CI 61.0, 100) and NPA 99.6% (95% CI 97.7, 99.9). PPA and NPA for prospectively collected SARS-CoV-2 anterior nasal specimens were 98.8% (95% CI 93.3, 99.8) and 98.3 (95% CI 95.1, 99.4), respectively. For flu A, PPA of 100% (95% CI 61.0, 100) and NPA of 99.6% (95% CI 97.8, 99.9) were observed. Lack of enrolled positive patients with flu B or RSV precluded the PPA calculation for those viruses. However, NPA for both flu B and RSV was 100% for the two specimen types. In retrospectively obtained nasopharyngeal specimens, PPA was 100% (95% CI 93.7, 100) for flu A, 100% (95% CI 93.8, 100) for flu B, and 98.4% (95% CI 91.5, 99.7) for RSV while NPA was 98.9% (95% CI 96.1, 99.7) for flu A, 98.9% (95% CI 96.1, 99.7) for flu B, and 100% (95% CI 97.9, 100) for RSV. Conclusion The BD MAX RVP assay showed a strong clinical performance in detecting and differentiating between the RNA of SARS-CoV-2, flu A and B, and RSV.

A-286 Performance Evaluation of Molecular Clostridium Difficile Assay using BD MaxTM System

Abstract Background Clostridium difficile (C.Diff) is a gram positive anaerobe producing Enterotoxin and Cytotoxin (toxin A and B respectively); toxin B has been reported to be essential for its virulence. It is estimated that C. Diff will cause over half a million infection yearly and one in 11 people over the age of 65 diagnosed with healthcare-associated C.Diff infection die within one month. It is the most common cause of acute diarrhea; residents in Long-Term Care Facilities (LTCF) are more prone to have C. Diff infection (CDI) because of their age, the frequent use of antibiotics, fragilities, co-morbidity, and living environment. Diagnosing CDI is based on clinical signs and symptoms as well as laboratory tests. Several tests available for diagnosing the infection which include: enzyme immunoassays, tissue culture cytotoxicity, anaerobic culture, glutamate dehydrogenase antigen and nucleic acid amplification. The BD MAX™ System is a PCR based assay that provides the sensitivity, specificity and faster turnaround. Methods The MAX™ System is an automated in vitro diagnostic test for the direct qualitative detection of the C. difficile toxin B gene (tcdB) in human liquid or soft stool specimens from patients suspected of having Clostridium difficile Infection (CDI).The test is performed directly on the specimen, utilizing real-time polymerase chain reaction (PCR) for the amplification of C. difficile toxin B gene (tcdB). The test utilizes fluorogenic sequence-specific hybridization probes for detection of the amplified DNA. The test was validated for accuracy, precision, and patient correlation to enzyme-immunoassay using Premier Toxins A & B is an enzyme immunoassay for the direct detection of Clostridium difficile toxin A and toxin B in stool samples. Statistical analyses were done using Analyse-it. Results The percentage agreement for precision, reproducibility, and accuracy were 100%. We had 100% agreement for positive patients on EIA and 85% for negative patients on EIA; however, upon investigation we found the discrepancies were due to false negative EIA results. Conclusion The BD Max gave the benefit of a fully automated with high sensitivity and specificity for the presence of toxin B producing C. Diff. The faster turnaround gives the physician the ability to diagnose CDI and prevent spreading of the disease to other patients. It is very important to remember that C.diff infection can be prevented with appropriate use of antibiotics and implementing antibiotic stewardship and infection control plan to prevent and stop spreading of the infection.

Applicability of an in-house extraction protocol in a Bruker Biotyper matrix-assisted laser desorption/ionization time-of-flight mass spectrometry system for the identification of Streptococcus agalactiae from broth-enriched vaginal/rectal swab specimens.

Early laboratory identification of group B Streptococcus (GBS, Streptococcus agalactiae) in the birth canal of pregnant women is critical for prompt administration of antimicrobial therapy and may further reduce the mortality rate due to GBS neonatal infection. A total of 164 vaginal/rectal swab specimens collected from pregnant women at 35-37 weeks of gestation were screened for GBS vaginal colonization. The matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS, Bruker Biotyper, Bruker Daltonik GmbH, Bremen, Germany) system was used to detect GBS from Carrot broth and LIM broth enrichment using an in-house extraction protocol. The results were compared to those by conventional broth-enriched culture/identification methods as the gold standard. BD MAX™ GBS assay (Becton Dickinson, Sparks, MD, USA) was also performed for Carrot broth-enriched specimen. Discordant results were investigated using the GeneXpert® GBS PCR assay (Cepheid Inc., Sunnyvale, CA, USA). Using the extraction protocol, 33 (20.1%) of the 164 specimens were positive in Carrot broth, and 19 (11.6%) were positive in LIM broth. Using the culture protocol, 38 (23.2%) samples in Carrot broth and 35 (21.3%) in LIM broth were positive. The sensitivity, specificity, and positive and negative predictive values using the extraction protocol in Carrot broth and LIM broth compared to the gold standard conventional culture/identification method were 86.8% and 50.0%, 100% and 100%, 100% and 100%, and 96.2% and 86.9%, respectively. The extraction protocol with MALDI-TOF MS from Carrot broth-enriched samples provides a more rapid turnaround time, lower cost, and acceptable sensitivity and specificity to correctly identify pathogens when compared to conventional culture/identification methods.

Using Real-Time PCR Fluorescence Reaction Values to Improve SARS-CoV-2 Virus Detection and Benefit Clinical Decision-Making.

This study aimed to compare the SARS-CoV-2 nucleic acid detection results of the BD MAX™ System and other platforms to formulate an optimized laboratory verification process. The re-examination of 400 samples determined as positive by BD MAX™ indicated that the inconsistency rate between BD MAX™ and the other platforms was 65.8%; the inconsistency rate of single-gene-positive results was as high as 99.2%. A receiver operating characteristic curve was drawn for the relative light unit (RLU) values of samples positive for a single gene, and RLU 800 was used as the cutoff. After setting the retest standard as single-gene positive and RLU ≥ 800, the number of the 260 BD MAX™ single-gene positives that needed to be confirmed again was 36 (13.8%) and the number that could be directly reported as negative was 224 (86.2%). This verification process can shorten the reporting period and speed up the epidemic adjustment time and turnover rate of special wards, thereby improving SARS-CoV-2 detection efficiency and clinical decision-making.

An analytic feasibility study of the BD MAX™ MDR-TB assay for testing of non-sputum specimens for detection of the Mycobacterium tuberculosis complex (MTBC) and isoniazid (INH) and rifampin (RIF) resistance

Rapid diagnosis of tuberculosis and drug resistance in extrapulmonary specimens can be challenging. The BD MAX™ multidrug resistant (MDR)-TB assay (BD MAX™) has demonstrated high sensitivity and specificity for the detection of the Mycobacterium tuberculosis complex (MTBC) as well as resistance to INH and Rifampin (RIF) in pulmonary specimens but has not been rigorously assessed in extrapulmonary samples. We evaluated the diagnostic accuracy of the BD MAX™ assay for the detection of MTBC and drug resistance in extrapulmonary specimens spiked with MTBC from the Johns Hopkins strain collection. A total of 1083 tests were performed across multiple sample types, with an overall percent agreement of 94.8% (795/839) for detection of MTBC and 99% (379/383) and 96.4% (323/335) for determination of INH and RIF resistance-conferring mutations, respectively. The BD MAX™ assay provides same day detection of MTBC and drug-resistance results and could be a beneficial diagnostic test in extrapulmonary sample types.

Clinical performance evaluation of BD SARS-CoV-2 reagents for BD MAXTM System in asymptomatic individuals

Transmission by asymptomatic individuals is a persistent hurdle in the effort to control the spread of SARS-CoV-2. Therefore, it is essential to continue developing assays and evaluate their performance for detection of SARS-CoV-2 in individuals without COVID-19 symptoms. In this study, 223 nasopharyngeal swab specimens collected from COVID-19 asymptomatic individuals were tested using the BD SARS-CoV-2 (RT-PCR-based) reagents for the BD MAX™ System and compared with results obtained with the Biomerieux BioFire® Respiratory RT-PCR Panel. Positive and negative percent agreements of 100% (95% CI, 84.5%–100%) and 99.0% (95% CI, 96.5%–99.7%), respectively, were observed for the BD SARS-CoV-2 assay. These results demonstrate the effectiveness of the BD SARS-CoV-2 assay for detecting SARS-CoV-2 in asymptomatic individuals and suggest that this assay can facilitate optimized case surveillance and infection control efforts. Investigations using larger sample sizes of asymptomatic individuals would be beneficial to support the findings in this study.

Assessment of SARS-CoV-2 tests costs and reimbursement tariffs readjustments during the COVID-19 pandemic.

While laboratories have been facing limited supplies of reagents for diagnostic tests throughout the course of the COVID-19 pandemic, national and international health plans, as well as billing costs, have been constantly adjusted in order to optimize the use of resources. We aimed to assess the impact of SARS-CoV-2 test costs and reimbursement tariff adjustments on diagnostic strategies in Switzerland to determine the advantages and disadvantages of different costs and resource saving plans. We specifically assessed the cost of diagnostic SARS-COV-2 RT-PCR using five different approaches: i) in-house platform, ii) cobas 6800® (Roche, Basel, Switzerland), iii) GeneXpert® SARS-CoV-2 test (Cepheid, Sunnyvale, CA, USA), iv) VIASURE SARS-CoV-2 (N1 + N2) Real-Time PCR Detection Kit for BD MAX™ (Becton Dickinson, Franklin Lake, NJ, USA), v) cobas® Liat® SARS-CoV-2 & Influenza A/B (Roche, Basel, Switzerland). We compared these costs to the evolution of the reimbursement tariffs. The cost of a single RT-PCR test varied greatly (as did the volume of tests performed), ranging from as high as 180 CHF per test at the beginning of the pandemic (February to April 2020) to as low as 82 CHF per test at the end of 2020. Depending on the time period within the pandemic, higher costs did not necessarily mean greater benefits for the laboratories. The costs of molecular reagents for rapid tests were higher than of those for classic RT-PCR platforms, but the rapid tests had reduced turnaround times (TATs), thus improving patient care and enabling more efficient implementation of isolation measures, as well as reducing the burden of possible nosocomial infections. At the same time, there were periods when the production or distribution of these reagents was insufficient, and only the use of several different molecular platforms allowed us to sustain the high number of tests requested. Cost-saving plans need to be thoroughly assessed and constantly adjusted according to the epidemiological situation, the clinical context and the national resources in order to always guarantee that the highest performing diagnostic solutions are available. Not all cost-saving strategies guarantee good analytical performance.

Evaluation of the clinical sensitivity and specificity of the BD Max™ Enteric Bacterial Panel for molecular detection of pathogens for acute gastroenteritis in the Singaporean population

PurposeAcute gastroenteritis (AGE) is caused by a wide range of pathogens. Culture methods for the detection of bacterial pathogens is time consuming and labour intensive. This study compared a same-day-to-result commercial molecular method using BD Max™ Enteric Bacterial Panel against conventional culture and laboratory-developed PCR assays (LDTs), and characterised the epidemiology of bacterial AGE in Singapore. MethodologyPCRs for Campylobacter spp., Salmonella spp., Shigella spp./Enteroinvasive Escherichia coli (EIEC) and Shiga toxin-producing E. coli (STEC)/Shigella dysenteriae were performed on the BD Max™ platform. Concurrent routine bacterial culture (“reference standard”) was performed for Campylobacter, Salmonella, Shigella, Vibrio and Aeromonas spp. In the event of a discrepancy, an “expanded reference standard” (bacterial culture with LDT) was used. ResultsThere were 299 stool specimens in the study, with no bacterial pathogens detected in 190 samples (63.5%). The positive samples (n = 109,36.5%) were detected with Salmonella (n = 57,19.1%), Campylobacter (n = 28,9.4%), Vibrio parahaemolyticus (n = 6,2.0%), Shigella/EIEC (n = 6,2.0%), ETEC (n = 4,1.3%), STEC (n = 2,0.7%), Aeromonas (n = 2,0.7%), Plesiomonas shigelloides (n = 1,0.3%) and 3(1.0%) co-infections. Compared to the “expanded reference standard”, conventional culture missed 38/112 (33.9%) pathogens. Conversely, testing by BD Max™ alone failed to detect 17 pathogens. BD Max™ reported seven (2.3%) false-positive results. ConclusionsBD Max™ increased the detection rate of bacterial AGE pathogens in the panel, but was limited by the absence of detection capability for Vibrio and Aeromonas spp.

Automation of RIDA®GENE Helicobacter pylori PCR on the BD MAX™ System.

PCR detection of Helicobacter pylori infection in gastric biopsies allows the detection of this bacterium and the mutations associated with macrolide resistance. The aim of this study was to evaluate the performance of RIDA®GENE H. pylori PCR (r-Biopharm) on a BD MAX™ System (Becton Dickinson). Two hundred ten gastric biopsies obtained were included. These biopsies were ground in nutrient broth. Two hundred microliters of this suspension was treated with proteinase K; 200 µL was transferred to a BD MAX™ sample tube then tested using RIDA®GENE H. pylori PCR reagents. In-house H. pylori PCR was used as a reference. The sensitivity of RIDA®GENE H. pylori PCR with BD MAX™ was 100%, the specificity was 99.08% (95% confidence interval (CI), 97.21-100%), the PPV was 99.02% (95% CI, 97.09-100%), and the NPV was 100% for the detection of H. pylori. The sensitivity was 97.14% (95% CI, 93.87-100%), the specificity was 100%, the PPV was 100%, and the NPV was 98.48%(95% CI, 96.08-100%) for categorization of macrolides resistance. The adaptation of RIDA®GENE H. pylori PCR on the BD MAX™ System is of considerable interest for microbiologists who seek to establish this assay in their laboratories.

Performances of the BD MAX™ CDIFF assay for the detection of toxigenic Clostridioides difficile using Cary-Blair preserved samples

Toxigenic Clostridioides difficile infection (CDI) is a high concern because of its increasing prevalence, among both nosocomial infection and community-acquired infection contexts. A total of 1320 prospective stool samples collected on FecalSwab™ (Cary-Blair medium) were screened using BD Max™ CDIFF assay (BDM). Results were compared to the routine algorithm including immunochromatographic testing for glutamate dehydrogenase (GDH) and toxin A/B (tox) using C. DIFF QUIK CHEK COMPLETE® followed by Xpert C. difficile assay in case of GDH+/tox- results. The prevalence of toxigenic C. difficile was estimated to 5.3% (n=70/1320) using the routine algorithm but to 7.4% (n = 98/1320) using BDM. The overall agreement between BDM and the routine algorithm was 97.4%. After resolution of discrepant results between BDM and the algorithm using Xpert C. difficile assay (unless already perform) and toxigenic culture performed by the French National Reference Laboratory, the overall agreement was increased to 99.4%, demonstrating the excellent performances of the test.

Evaluation of Factors that Affect the Performance of COVID-19 Molecular Assays Including Presence of Symptoms, Number of Detected Genes and RNA Extraction Type.

Background and AimsRapid and accurate detection of COVID-19 is crucial for mitigation of the pandemic. We evaluated the performance of six molecular kits and the effect of several factors on the performance of the kits.Materials and MethodsTwo hundred and four nasopharyngeal samples were collected from participants aged ≥18 years at the Baruch Padeh Medical Center Poriya, Israel, between June and August 2020. Samples were tested by: Allplex 2019‐nCOV Assay (Seegene), Real‐Time Fluorescent RT‐PCR Kit for Detecting SARS-2019-nCoV (BGI Genomics), Xpert® Xpress SARS-CoV-2 test (Cepheid), Simplexa® COVID-19 Direct Kit (Focus Diagnostics), BD SARS-CoV-2 Reagents for BD MAX™ System (BD), and Logix Smart™ Coronavirus Disease 2019 (COVID-19) Test kit (CO-DIAGNOSTICS).ResultsXpert® Xpress SARS-CoV-2 test and Logix Smart™ COVID-19 Kit had the highest (91.2%) and the lowest (74.5%) sensitivity, respectively. Symptoms were a predictor of a positive result. Traditional assays had a higher minimum cycle threshold (min Ct), i.e. detected lower viral load, compared to rapid assays (p = 0.012). Samples of symptomatic participants had lower min Ct, than samples of asymptomatic participants (p < 0.001). Additionally, the more genes were detected, the lower the min Ct (p < 0.001), indicating that a greater percentage of the viral genome was amplified.ConclusionsTaken together, most assays had overall good performance. Since several factors affect the performance of kits, each laboratory must be familiar with its kit’s limitations in order to produce the most reliable results.Supplementary InformationThe online version contains supplementary material available at 10.1007/s40291-021-00574-y.

Reliable Diagnostics of SARS-CoV-2 Infections Using One- and Two-Gene Molecular Tests for a Viral RNA Detection-Results Questioning Previous Observations.

SARS-CoV-2 is a new virus from the Coronaviridae family and its rapid spread is now the most important medical problem worldwide. Currently used tests vary in the number and selection of SARS-CoV-2 target genes. Meanwhile, the choice of the appropriate target gene may be important in terms of a reliable detection of a viral RNA. As some researchers questioned the sensitivity of the monogenic VIASURE SARS-CoV-2 S gene Real Time PCR Detection Kit (CerTest Biotec, Zaragoza, Spain) in mid-2020, the aim of the study was to evaluate the usefulness of this kit, used along with the BD MAX™ System (Becton Dickinson, East Rutherford, NJ, USA), and compare the results with two-gene Bosphore Novel Coronavirus (2019-nCoV) Detection Kit v1 (Anatolia Diagnostics and Biotechnology Products Inc., Istanbul, Turkey). Both tests were carried out on 306 nasopharyngeal/oropharyngeal swabs. The consistent results (72 positive and 225 negative results found simultaneously in both kits) were obtained for 297 (97.1%) samples altogether, while discrepancies between the results of the evaluated tests were observed for nine (2.9%) specimens. There were no statistically significant differences between the method used and the frequency of positive results. Both tests, targeted at detecting one and two genes, are effective in SARS-CoV-2 RNA detection.