Cobas Liat Research Articles

Assessment of DNA/RNA Defend Pro: An Inactivating Sample Collection Buffer for Enhanced Stability, Extraction-Free PCR, and Rapid Antigen Testing of Nasopharyngeal Swab Samples.

This study comprehensively evaluated the DNA/RNA Defend Pro (DRDP) sample collection buffer, designed to inactivate and stabilize patient samples. The primary objectives were to assess DRDP's efficacy in ensuring sample stability, facilitating extraction-free polymerase chain reaction (PCR), and ensuring compatibility with rapid antigen testing (RAT). Ninety-five diagnostic nasopharyngeal swab samples tested for influenza virus (influenza A), respiratory syncytial virus (RSV A), and/or severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were 10-fold diluted with DRDP and anonymized. Initial characterization and retesting of these samples using cobas Liat confirmed 88 samples as positive, validating the presence of viral targets. Results from rapid antigen testing showed lower sensitivity compared to nucleic acid amplification testing (NAAT) but maintained perfect specificity, with 40 out of 88 positive samples by cobas Liat also testing positive for RAT. Direct RT-qPCR of DRDP-diluted samples demonstrated robust compatibility, with 72 out of 88 samples positive for cobas Liat also testing positive by direct RT-qPCR. Non-concordant results could be explained by the 200-fold lower input of extraction-free NAAT. Stability testing involved incubating 31 positive samples at 4 °C, 20 °C, and 37 °C for 7 days, with extraction-free NAAT. DRDP guaranteed viral RNA stability at all temperatures for influenza A, SARS-CoV-2, and RSV A, showing stability up to 7 days at 4 °C. In conclusion, DRDP is an effective stabilizing medium compatible with direct RT-qPCR and rapid antigen testing and shows great potential for optimizing diagnostic processes, particularly in resource-limited or time-sensitive scenarios.

Heparin-mediated PCR interference in SARS-CoV-2 assays and subsequent reversal with heparinase I

Heparin is postulated to block the interaction of SARS-CoV-2 with highly glycosylated proteins which are critical for binding the angiotensin-converting enzyme 2 (ACE2), an essential mechanism for host-cell entry and viral replication. Intranasal heparin is under investigation for use as a SARS-CoV-2 preventative in the IntraNasal Heparin Trial (INHERIT, NCT05204550). Heparin directly interferes with real-time quantitative polymerase chain reaction (RT-qPCR), the gold standard for SARS-CoV-2 detection. This study aimed to investigate the magnitude of heparin interference across various clinical laboratory testing platforms, and the reversal of any interference by degradation of heparin using the heparinase I enzyme in nasopharyngeal swab (NP) samples for SARS-CoV-2 analysis by RT-qPCR. Heparin-mediated PCR interference was evident at heparin concentrations as low as 10 IU/mL across all platforms tested, with the exclusion of the Hologic Panther Aptima SARS-CoV-2 assay. Rates of false negative or invalid results increased with increasing heparin concentrations on all platforms, except the Hologic Panther Aptima and Roche Cobas LIAT. Heparinase I reversed heparin-mediated PCR inhibition across in all samples tested, except those with initial Ct values >35. Our study shows that the use of heparin-containing nasal sprays interferes with the detection of SARS-CoV-2 in NP swab samples by RT-qPCR, a phenomenon that is not well recognised in the literature. Furthermore, this study has also demonstrated that heparin-mediated PCR inhibition can be prevented through heparinase I treatment, demonstrating restoration of clinically significant results with Ct values <35.

The value of point-of-care tests for the detection of SARS-CoV-2 RNA or antigen in bronchoalveolar lavage fluid

BackgroundTransmission of SARS-CoV-2 from donor to recipient is a clinically relevant risk for developing severe COVID-19 after lung transplantation (LTx). This risk of iatrogenic transmission can be reduced by timely detection of viral RNA or antigen in samples of bronchoalveolar lavage (BAL) fluid obtained at the time of lung procurement. We aimed to retrospectively evaluate the detection of SARS-CoV-2 RNA or antigen in BAL fluid samples using three point-of-care tests (POCTs). MethodsBAL fluid samples came from patients hospitalized in an intensive care unit during the COVID-19 pandemic. These pandemic samples were scored as positive or negative for SARS-CoV-2 by a RT-qPCR comparator assay for orf1ab. Three commercially available POCTs were then evaluated: cobas SARS-CoV-2 & Influenza A/B assay with the cobas Liat RT-qPCR system (Roche Diagnostics), ID NOW COVID-19 and COVID-19 2.0 (Abbott), and SARS-CoV-2 Rapid Antigen Test (RAT) (Roche Diagnostics). Samples from the pre-pandemic era served as negative controls. ResultsWe analyzed a total of 98 BAL fluid samples, each from a different patient: 58 positive pandemic samples (orf1ab Ct<38), 20 putatively negative pandemic samples (orf1ab Ct≥38), and 20 pre-pandemic samples. Univariate logistic regression shows that the probability of detection was highest for cobas Liat, followed by ID NOW, and then RAT. Of clinical relevance, cobas Liat detected SARS-CoV-2 RNA in 30 of the 31 positive pandemic samples that were collected within 10 days after RT-qPCR diagnosis of SARS-CoV-2 infection. None of the 20 pre-pandemic samples had a false-positive result for any POCT. ConclusionsPOCTs enable the detection of SARS-CoV-2 RNA or antigen in BAL fluid samples and may provide additional information to decide if donor lungs are suitable for transplantation. Detection of respiratory pathogens with POCTs at the time of donor lung procurement is a potential strategy to increase safety in LTx by preventing iatrogenic transmission and severe postoperative infections.

Performance evaluation of the cobas SARS-CoV-2 Duo, a novel qualitative and quantitative assay, for the detection of SARS-CoV-2 RNA.

Viral load quantification of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a critical measure for monitoring clinical responses of patients with COVID-19. The cobas SARS-CoV-2 Duo (Roche Molecular Systems, Inc.) uses the cobas 6800/8800 platform and is an automated real-time reverse transcription PCR (RT-PCR) assay for the qualitative detection of SARS-CoV-2 RNA (ORF1a and ORF1a/b non-structural regions) in nasal and nasopharyngeal specimens. This assay also performs quantitation of the SARS-CoV-2 RNA level in the collected specimen. The precision, accuracy, and linearity of the cobas SARS-CoV-2 Duo test were assessed and correlated with the cycle threshold (Ct) value of the cobas SARS-CoV-2 assay, and the cobas Liat SARS-CoV-2 and influenza A/B assay (Inf A/B) (cobas Liat) in 201 clinical nasopharyngeal swab specimens. The analytical measurement range of the cobas SARS-CoV-2 Duo has been verified to be 1.0E + 02 IU/mL to 1.0E + 09 IU/mL. The between- and within-run precision evaluation and the linearity results (R 2 = 0.9961) of the cobas SARS-CoV-2 Duo were acceptable based on the verification criteria. A total of 201 nasopharyngeal specimens were evaluated. The positive, negative, and total agreements between the cobas SARS-CoV-2 Duo and the cobas SARS-CoV-2 assay were 93.5% (157 of 168), 75% (33 of 44), and 92.5% (186 of 201), respectively. The qualitative results (Ct values) from the cobas SARS-CoV-2 and the cobas Liat demonstrated good agreement with the quantitative results from the cobas SARS-CoV-2 Duo assay. In conclusion, the diagnostic performance of the cobas SARS-CoV-2 Duo assay is appropriate. It is a precise, accurate, and sensitive method for the detection of SARS-CoV-2 RNA and is comparable to two qualitative assays. IMPORTANCE Quantitative SARS-CoV-2 tests for viral load are necessary to guide patient treatment, as well as to determine infection control measures and policies. Although the real-time RT-PCR assays can report the Ct value to estimate the viral load, there are several serious concerns regarding the use of Ct values. Importantly, Ct values can vary significantly among between- and within-run methods. The diagnostic performance of the cobas SARS-CoV-2 Duo is appropriate. It is a precise, accurate, and sensitive method for the detection of SARS-CoV-2 RNA and is comparable to two qualitative assays (the cobas SARS-CoV-2 and the Liat cobas SARS-CoV-2 and Inf A/B). In contrast, using the Ct value to estimate viral load is not reliable, and utilization of a quantitative detection test, such as the cobas SARS-CoV-2 Duo, to accurately measure the viral load is needed.

A study to assess the impact of the cobas point-of-care RT-PCR assay (SARS-CoV-2 and Influenza A/B) on patient clinical management in the emergency department of the University of California at Davis Medical Center.

Rapid detection of SARS-CoV-2 is crucial for reduction of transmission and clinical decision-making. Several rapid (<30min) molecular point-of-care (POC) tests based on nucleic acid amplification exist for diagnosis of SARS-CoV-2 & Influenza A/B infections. This unblinded, pre-post study enrolled consecutive patients with symptoms/signs consistent with SARS-CoV-2 infection presenting to the University of California, Davis emergency department (ED). Outcomes following implementation of the cobas® SARS-CoV-2 & Influenza A/B test for use on the cobas Liat System (intervention: December 2020-May 2021) were compared with previous standard-of-care using centralized laboratory reverse transcriptase polymerase chain reaction (RT-PCR) methods (control: April 2020-October 2020). Electronic health records of 8879 symptomatic patient visits were analyzed, comprising 4339 and 4540 visits and 538 and 638 positive SARS-CoV-2 PCR test results in the control and intervention periods, respectively. Compared with the control period, turnaround time (TAT) was shorter in the intervention period (median 0.98vs 12.30h; p<0.0001). ED length of stay (LOS) was generally longer in the intervention period compared with the control period, but for those SARS-CoV-2-negative who were admitted, ED LOS was shorter (median 12.53vs 17.93h; p<0.0001). The rate of antibiotic prescribing was lower in the intervention than in the control period (42.86% vs 49.16%; p<0.0001) and antiviral prescribing was higher (7.64% vs 5.49%; p<0.0001). This real-world study confirms faster TAT with a POC RT-PCR method in an emergency care setting and highlights the importance of rapid SARS-CoV-2 detection to aid patient management and inform treatment decisions.

Evaluation of pharmacist guided intervention using procalcitonin and respiratory virus testing

IntroductionAcute respiratory infections make up a sizable percentage of emergency department (ED) visits and many result in antibiotics being prescribed. Procalcitonin (PCT) has been found to reduce antibiotic use in both outpatient and critical care settings, yet remains underused in the ED. This study aimed to evaluate whether point of care molecular influenza and Respiratory Syncytial Virus (RSV) testing, PCT, and a pharmacist driven educational intervention in aggregate optimizes antibiotic and antiviral prescribing in the ED setting. MethodsA randomized trial of the Cobas Liat Flu/RSV Assay, procalcitonin, and the use of pharmacist-led education in patients 0–50 years of age being seen in the ED for Influenza Like Illness (ILI) or acute respiratory illness. The study enrolled 200 ED patients between March 2018 and April 2022. ResultsThere was little difference in antibiotic or antiviral prescribing between the intervention and control groups in this study (39%–32% = 7.0%, 95% CI: −6.2, 20.2, P = 0.30). However, a post-hoc analysis of the use of procalcitonin showed results were used as indicated in the ED (P = 0.001). ConclusionPCT can be used in both adult and pediatric populations to help guide the decision of whether to treat with antibiotics in the ED setting. Pharmacist guided education may not be a driving factor.

Evaluation of the cobas Liat detection test for SARS-CoV-2 and influenza viruses following the emergence of the SARS-CoV-2 Omicron variant

ObjectivesThis study assessed the clinical performance of the cobas Liat SARS‑CoV‑2 & Influenza A/B assay (LiatCOVID/flu) for the detection of both severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza viruses during the SARS-CoV-2 Omicron outbreak. MethodsResidual nasopharyngeal swab samples (NPS) previously tested with cobas SARS-CoV-2 & Influenza A/B for SARS-CoV-2 and with the Allplex Respiratory Panel 1 for influenza viruses were collected. All samples were submitted to the LiatCOVID/flu assay. ResultsA total of 1147 samples were collected comprising 167 SARS-CoV-2-positive, 556 SARS-CoV-2-negative, 224 influenza-positive, and 200 influenza-negative cases. The positive percent agreement (PPA)/negative percent agreement (NPA) of LiatCOVID/flu for SARS-CoV-2 and influenza viruses compared to the previously tested methods were 100% of 100% and 99.6% of 100%, respectively. ConclusionsThe LiatCOVID/flu assay shows an acceptable performance in the detection of SARS-CoV-2 and influenza viruses using NPS samples.

314. Performance of Saliva Compared to Nasopharyngeal Swab in Detection of SARS-CoV-2 at a Field Site in Rural Guatemala Using the Roche Cobas® Liat® Point-of-Care Assay

Abstract Background Saliva samples are less invasive but not considered the gold standard for detecting SARS-CoV-2, and they are not validated for the Roche Cobas® Liat® platform. We aimed to evaluate the performance of a saliva sample compared to nasopharyngeal (NP) swab in the detection of SARS-CoV-2 on the Roche Cobas® Liat® platform at a research site in rural Guatemala. Methods Adults in an existing cohort study with influenza-like illness (ILI) provided clinical data and underwent NP swab (Copan) collection by trained nurses. Swabs were immediately placed into universal transport media (UTM), stored at 2-8 °C for less than 30 minutes and then tested on the Cobas Liat platform for SARS-CoV-2. Consenting subjects who had not eaten or drank in the last 2 hours were asked to provide a 5-mL saliva sample directly into an RNAse free container. The saliva sample remained at 2-8 °C for 24 hours, then diluted 1:2 with 0.85% saline (to reduce viscosity) and run on the same assay. We used descriptive statistics to compare the performance of saliva to NP swabs. Results Of the 28 subjects screened (1/10/22 - 4/26/22), 23 (82%) were consented and enrolled. The majority of subjects were male (78.3%) with a mean age of 31 years (range: 18-59 years). Of the 23 subjects enrolled, 14 (30.4%) reported fever and cough, 16 (34.8%) reported cough only, 14 (30.4%) reported fever only, and 2 (4.3%) reported cough and nasal congestion. The median symptom duration was 3.0 days (IQR: 1.5-5 days). Of the 23 subjects, 5 (23.7%) tested positive for SARS-CoV-2 in both sample types (NP swab and saliva); 3 (13%) were discordant, including 1 (4.3%) saliva-positive only and 2 (8.7%) NP-positive only. Compared to NP swab, preliminary performance of saliva in detection of SARS-CoV-2 included a sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of 71.4%, 93.7%, 87%, 83.3%, and 88.2%, respectively. The Fisher’s exact test p-value (0.003) shows concordance between both tests. Conclusion Our preliminary results show good precision between NP and saliva samples in detection of SARS-CoV-2 on the Roche Cobas® Liat® platform. Ongoing data collection will provide greater insight on the discordant results, but our findings support the continued use of saliva in the detection of SARS-CoV-2 in this population. Disclosures Molly Lamb, PhD, Pfizer: Grant/Research Support Edwin J. Asturias, MD, Curevac: DSMB Member|Fundacion para la Salud Integral de los Guatemaltecos: Board Member|Inovio: DSMB Member|Merck: Honoraria|Pfizer: Grant/Research Support Diva Calvimontes, n/a, Pfizer: Grant/Research Support Daniel Olson, MD, Fundacion para la Salud Integral de los Guatemaltecos: Board Member|Pfizer: Grant/Research Support|Roche: Grant/Research Support.

Distribution of Viral Respiratory Infections during the COVID-19 Pandemic Using the FilmArray Respiratory Panel.

This study was conducted to evaluate the distribution of respiratory viral pathogens in the emergency department during the coronavirus disease 2019 (COVID-19) pandemic. Between May 2020 and September 2022, patients aged between 0.1 and 98 years arrived at the emergency department of Asia University Hospital, and samples from nasopharyngeal swabs were tested by the FilmArrayTM Respiratory Panel (RP). SARS-CoV-2 positivity was subsequently retested by the cobas Liat system. There were 804 patients for whom the FilmArrayTM RP was tested, and 225 (27.9%) of them had positive results for respiratory viruses. Rhinovirus/enterovirus was the most commonly detected pathogen, with 170 (61.8%) cases, followed by adenovirus with 38 (13.8%), SARS-CoV-2 with 16 (5.8%) cases, and coronavirus 229E, with 16 (5.8%) cases. SARS-CoV-2 PCR results were positive in 16 (5.8%) cases, and there were two coinfections of SARS-CoV-2 with adenovirus and rhinovirus/enterovirus. A total of 43 (5.3%) patients were coinfected; the most coinfection was adenovirus plus rhinovirus/enterovirus, which was detectable in 18 (41.9%) cases. No atypical pathogens were found in this study. Intriguingly, our results showed that there was prefect agreement between the detection of SARS-CoV-2 conducted with the cobas Liat SARS-CoV-2 and influenza A/B nucleic acid test and the FilmArrayTM RP. Therefore, the FilmArrayTM RP assay is a reliable and feasible method for the detection of SARS-CoV-2. In summary, FilmArrayTM RP significantly broadens our capability to detect multiple respiratory infections due to viruses and atypical bacteria. It provides a prompt evaluation of pathogens to enhance patient care and clinical selection strategies in emergency departments during the COVID-19 pandemic.

Clinical performance of SARS-CoV-2 detection on the cobas Liat using water gargle samples

Spring water gargle (SWG) is a suitable, non-invasive, alternative specimen for SARS-CoV-2 detection by RT-PCR. This study sought to evaluate the performance of the cobas Liat point-of-care system for the detection of SARS-CoV-2 in SWG samples. SWG samples and standard oral and nasopharyngeal swab (ONPS) were collected simultaneously from participants in a COVID-19 screening clinic, in November and December 2020. Both sample types were analyzed in parallel on the cobas Liat platform and with the Seegene Allplex 2019-nCoV assay. Among the 110 participants, 53% had compatible symptoms and 71% had a contact with a confirmed COVID-19 case. Only two (1.8%) individuals had neither symptoms nor contact. Amongst 110 paired samples, 25 (23%) were positive for SARS-CoV-2 on the cobas Liat for a least one sample type, with a kappa coefficient of 0.92. Agreement between the cobas Liat platform and the Seegene assay was also excellent (kappa coefficient values of 0.94 and 0.95). Two SWG samples failed to provide a positive result when their ONPS pair was positive, but their cycle threshold (Ct) values were >35 on the Seegene assay, reflecting a low viral load. Overall, the performance of the cobas Liat platform is excellent for the detection of SARS-CoV-2 in SWG samples in a high pre-test probability population.

Guidelines for COVID-19 Laboratory Testing for Emergency Departments From the New Diagnostic Technology Team of the Taiwan Society of Emergency Medicine.

COVID-19 tests have different turnaround times (TATs), accuracy levels, and limitations, which emergency physicians should be aware of. Nucleic acid amplification tests (NAATs) can be divided into standard high throughput tests and rapid molecular diagnostic tests at the point of care (POC). The standard NAAT has the advantages of high throughput and high accuracy with a TAT of 3-4 hours. The POC molecular test has the same advantages of high accuracy as standard high throughput PCR, but can be done in 13-45 minutes. Roche cobas Liat is the most commonly used machine in Taiwan, displaying 99%-100% sensitivity and 100% specificity, respectively. Abbott ID NOW is an isothermal PCR-based POC machine with a sensitivity of 79% and a specificity of 100%. A high rate of false positives and false negatives is associated with rapid antigen testing. Antibody testing is mostly used as part of public health surveys and for testing for immunity.

The Impact of Point-of-Care Polymerase Chain Reaction Testing on Prescribing Practices in Primary Care for Management of Strep A: A Retrospective Before-After Study.

BackgroundRapid antigen detection tests (RADTs) are the standard of care (SOC) for testing in patients with suspected group A β-hemolytic Streptococcus (Strep A) infection. Due to lower sensitivity, guidelines recommend confirmatory microbiological culture following negative RADT results. This process is time-consuming, and adherence is often poor, resulting in high rates of inappropriate antibiotic prescribing. We sought to evaluate the impact of switching from RADTs to point-of-care (POC) polymerase chain reaction (PCR) testing on use of antibiotics in primary care, when used as part of an antibiotic stewardship initiative.MethodsIn this retrospective before–after study, electronic medical records of any patients presenting with suspected acute pharyngitis (June 2018–May 2019) across 15 outpatient primary care clinics were evaluated. Strep A was detected using the cobas Strep A assay (cobas Liat system).ResultsAnalysis of 10 081 eligible patient records showed that POC PCR testing resulted in a 44.1% reduction in antibiotic prescribing for patients with a negative POC PCR test result (10.1% PCR vs 18.0% RADT; P < .0001). Rates of antibiotic prescription varied across clinical sites, ranging between 10.7% and 33.8% and 12.4% and 34.4% during the use of PCR tests and RADTs, respectively. POC PCR had no impact on prescription rates in patients with positive POC test results compared to RADTs (76.2% vs 76.5%, respectively). More than 99% of antibiotics were prescribed during the initial primary care encounter.ConclusionsAs part of a broader antibiotic stewardship initiative, implementation of POC PCR as SOC in outpatients with acute pharyngitis symptoms reduced the volume of inappropriate antibiotic prescriptions.

Discordant SARS-CoV-2 RNA results obtained using the Roche cobas Liat SARS-CoV-2

Between 05/08/2021 and 04/11/2021 NSW Health Pathology (NSWHP) has been collating data regarding discordant SARS-CoV-2 RNA results obtained using the Roche cobas Liat SARS-CoV-2. Over this time approximately over 120,000 Liat SARS-CoV-2 assays were performed across NSWHP sites, with 6227 (∼5%) of samples testing positive. Seventy (0.06%) discordant results for SARS-CoV-2 RNA were recorded when the result obtained on the Liat assay was compared to the result obtained on an alternative platform using the same sample.

Rapid and Safe Detection of SARS-CoV-2 and Influenza Virus RNA Using Onsite Quantitative PCR Diagnostic Testing From Clinical Specimens Collected in Molecular Transport Medium.

BACKGROUNDThe ability to rapidly detect SARS-CoV-2 and influenza virus infection is vital for patient care due to overlap in clinical symptoms. Roche’s cobas® Liat® SARS-CoV-2 & Influenza A/B Nucleic Acid Test used on the cobas® Liat® was granted approval under FDA’s Emergency Use Authorization (EUA) for nasopharyngeal (NP) and nasal swabs collected in viral/universal transport medium (VTM/UTM). However, there is a critical need for media that inactivates the virus, especially when specimens are collected in decentralized settings. This study aimed to investigate the use of PrimeStore Molecular Transport Medium® (PS-MTM®), designed to inactivate/kill and stabilize RNA/DNA for ambient transport and pre-processing of collected samples.METHODSA limit of detection (LOD) using serially diluted SARS-CoV-2 RNA in PS-MTM® and routine UTM was established using standard qPCR. Additionally, a clinical panel of NP and oral swabs collected in PS-MTM® collected during the 2020 coronavirus disease 2019 (COVID-19) pandemic were evaluated on the cobas® Liat® and compared to ‘gold standard’ qPCR on an ABI-7500 instrument.RESULTSSARS-CoV-2 RNA LOD using standard qPCR was equivalent on the cobas® Liat® instrument. cobas® Liat® detection from oral/NP swabs in PS-MTM® media exhibited equivalent positive percent agreement (100%) and negative percent agreement (96.4%).CONCLUSIONPS-MTM® and the Roche cobas® Liat® are compatible and complimentary devices for respiratory specimen collection and rapid disease detection, respectively. PS-MTM® is equivalent to standard VTM/UTM with the added benefit of safe, non-infectious sample processing for near-patient testing.

Comparative Evaluation of Two Automated Multiplex RT-PCR Tests for Rapid Detection of Influenza and Respiratory Syncytial Viruses.

Rapid and accurate diagnosis of influenza virus (Flu) and respiratory syncytial virus (RSV) is important for managing both the patient and laboratory. We compared the cobas Influenza A/B & RSV assay (cobas Liat) with the Simplexa Flu A/B & RSV assay (Simplexa) to evaluate which test method is more advantageous considering the resources of the laboratory and results of test performance. A total of 236 respiratory specimens from patients referred for respiratory virus testing were retrospectively evaluated; 53 specimens tested positive for each of Flu A, Flu B, and RSV, and 77 specimens tested negative based on the results of the reference method, i.e., the Seegene Allplex Respiratory Panel 1/2/3 (Seegene, Seoul, Korea). The turnaround time (TAT) was 20 minutes per specimen for cobas Liat and 78 minutes per eight speci-mens for Simplexa. The total hands-on time was around one minute per specimen for both tests. The specimen volume required for testing was 200 µL for cobas Liat and 50 µL for Simplexa. Seegene Allplex Respiratory Panel 1/2/3 was used as the reference method. The number of invalid results was 1 (0.4%) for cobas Liat and 10 (4.2%) for Simplexa (p < 0.05). All results were consistent with those of the reference method in cobas Liat. The sensitivity and specificity for Flu A, Flu B, and RSVA were 100% with Simplexa. However, the sensitivity for RSVB was 80.0% with Simplexa, which was a statistically significant difference with the finding for cobas Liat (p < 0.05). Comparison of the cycle threshold (Ct) values of RSV for Simplexa with the reference method showed correlation as continuous variables (p < 0.001) with a higher propensity for obtaining Ct values with Simplexa, the exception being the six false negative results; their Ct values were more than 30 in the reference method. Cobas Liat showed accurate performance with a rapid TAT and a good workflow efficiency. Cobas Liat is more efficient than Simplexa as a point-of-care test for the detection of RSV.

Associations Between Relative Viral Load at Diagnosis and Influenza A Symptoms and Recovery.

BackgroundRapid point-of-care polymerase chain reaction (PCR) diagnostic tests generally provide a qualitative result of positive or negative only. Additional information about the relative viral load could be calculated. Such quantitative information might be useful for making treatment decisions.MethodsWe enrolled students at a university health center who presented with cough and 1 additional flu-like symptom from December 2016 to February 2017. Data were collected before, during, and 5 days after the clinic visit. All those enrolled in the study received a point-of-care PCR test (cobas Liat). For those patients that tested positive for influenza A, we investigated correlations between the relative viral load and measures of disease severity and recovery.ResultsOne hundred thirty-five students tested positive for influenza A. We found a positive correlation between viral load and body temperature. Time since symptom onset seemed to have a negative correlation but was not statistically significant. We did not find any correlations between viral load and overall symptom severity or outcomes related to recovery.ConclusionsAlthough we found a correlation between relative viral load and body temperature, for our study population of young, overall healthy adults, we did not find that relative viral load provided additional information that could help in determining treatment and disease outcomes. It could be that viral load does provide useful additional information for other groups of patients, such as young children or older adults. Further studies on those populations are warranted.

Performance Comparison of a Novel Rapid Stand-alone Molecular Test and a 2-Step Diagnostic Algorithm for Clostridioides difficile Detection in Children.

We aimed to evaluate diagnostic performance of the cobas® Liat® Cdiff test, a novel single-step automated polymerase chain reaction (PCR) assay for rapid diagnosis of toxigenic Clostridioides difficile infection (CDI) in stool samples from children with clinical symptoms of CDI. Assessment of cobas Liat Cdiff diagnostic yield, time of analytical process and agreement of results with those of a 2-step diagnostic algorithm. The sequential algorithm combined an enzyme immunoassay (EIA) targeting antigen glutamate dehydrogenase (GDH), enterotoxin-A and cytotoxin-B, and a confirmatory PCR in EIA GDH-positive and toxin-negative samples. Fresh stool samples were collected prospectively from patients 2-18 years of age that were attended in Hospital Sant Joan de Deu (Barcelona, Spain) during December 2018-August 2019. A total of 122 specimens were collected from 91 children (mean age, 8 years; 69.7% male). cobas Liat Cdiff identified 24 (19.7%) positive samples. EIA yielded 97 (79.5%) GDH- and toxin-negative results, 11 (9.0%) GDH- and toxin-positive results, and 14 (11.5%) GDH-positive and toxin-negative results, of which 11 (9.0%) were positive for the toxin by the confirmatory PCR. Overall, GDH- and toxin-positive samples detected by the sequential algorithm were 22 (18.0%). Comparatively, the new test reduced time of the analytical process significantly (20 vs. 35.4 minutes, P < 0.001). Use of cobas Liat Cdiff showed similar detection yield compared with a 2-step diagnostic algorithm that combined an EIA and a confirmatory PCR while decreasing the time of the analytical process markedly in stool samples from children suspected of CDI.

Evaluation of cobas Influenza A/B & RSV Test for Diagnosis of Equine Influenza

A rapid and sensitive diagnostic method is needed to help prevent the spread of equine influenza virus. The cobas Influenza A/B & RSV test for the cobas Liat system (Roche Diagnostics) is based on real-time reverse transcription polymerase chain reaction and is designed to broadly detect influenza A virus RNA within 20 minutes. It detected a broad range of equine influenza virus strains, and detected equine influenza virus RNA from nasal swabs of infected horses at the same level as real-time reverse transcription polymerase chain reaction, although it returned some invalid results (7.7%). This suggests that cobas Influenza A/B & RSV test is highly sensitive to equine influenza virus, but should be improved to reduce the rate of invalid results.

Evaluation of a community pharmacy–based influenza and group A streptococcal pharyngitis disease management program using polymerase chain reaction point-of-care testing

ObjectivesThe purpose of this study was to demonstrate the feasibility of implementing a Clinical Laboratory Improvement Amendments–waived real-time polymerase chain reaction (PCR) molecular test into a community pharmacy setting as part of a collaborative influenza and group A Streptococcus (GAS) disease management program. Setting and participantsTwo community pharmacy sites in Tennessee. Practice descriptionPatients presenting to the pharmacy with symptoms consistent with influenza or GAS from November 1, 2016, to April 30, 2018. Practice innovationInfluenza and GAS management programs based on previously developed protocols occurred at 2 community pharmacies in Tennessee. Pharmacies used the Cobas Liat testing system (Roche Diagnostics). Based on test results and under a collaborative practice agreement, pharmacists dispensed prescription medications for patients with a positive test: oseltamivir for influenza and amoxicillin for GAS. Patients with negative tests were treated with over-the-counter (OTC) medications or referred. Patients testing negative for GAS were asked to consent to having a second throat swab sent for culture. EvaluationNumber of patients tested, point-of-care test results, and treatment received. ResultsTwo hundred and two patients received care at the 2 pharmacies (116 for influenza, 46 for GAS, and 43 for both). Sixty (38%) tested positive for influenza, with 51 receiving an antiviral prescription, and 16 (18%) tested positive and were treated for GAS. No patient testing negative for either or positive for influenza was dispensed an antibiotic. For patients consenting to a follow-up culture, all GAS cultures sent for confirmatory testing were negative. ConclusionA protocol-driven community pharmacy–based disease management program using real-time PCR testing for influenza and GAS was able to offer appropriate treatment to patients without overuse of antibiotics.

Assay Integrity of a PCR Influenza Point-of-Care Test Remains Following Artificial System Contamination.

Healthcare providers who have access to tests at the point of care (POC) are increasingly requesting the same performance from the POC test as they expect from the laboratory. With the introduction of the cobas® Liat instrument, highly sensitive molecular diagnostic testing can be performed closer to the patient in CLIA-waived, POC settings. As more sensitive tests become available, there is concern regarding contamination of instrumentation owing to improper handling, mistakes made when processing, or environmental contamination. Recent concerns were raised when a nurse performed environmental surveillance for flu A/B by inserting a dry swab into the cobas Liat instrument and then ran it as a sample on the instrument, generating a positive result. This finding stimulated questions about the possibility of system contamination contributing to false-positive results, ultimately leading to the possibility of providing incorrect treatment to patients. To assess the likelihood of system contamination contributing to the generation of false-positive results, in this study we contaminated a cobas Liat System with flu A/B-positive control material. The system contamination was then assessed by swabbing exposed surfaces. Following confirmed system contamination, negative control samples were processed to determine whether system contamination had an impact on the expected negative results. Instrument contamination was confirmed, and no detectable flu A/B signal was observed for any of the negative control tubes run immediately following confirmation of system contamination. Environmental contamination of the Liat instrument does not have an impact on the integrity of the result.