Comparison of five SARS-CoV-2 rapid antigen detection tests in a hospital setting and performance of one antigen assay in routine practice: a useful tool to guide isolation precautions?

BACKGROUND: In a hospital setting, there is a need for rapid detection of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) to guide isolation measures and targeted admission. AIM: To evaluate the diagnostic performance of five SARS-CoV-2 rapid nucleocapsid protein antigen detection (RAD) assays (Biosynex, Biotical, Orient Gene, Panbio and SD Biosensor), and describe the performance and impact of implementation of the SD Biosensor assay in an emergency department. METHODS: Sensitivity and specificity of the five RAD assays were analysed on 100 respiratory samples: 60 real-time reverse transcriptase polymerase chain reaction (rRT-PCR)-confirmed SARS-CoV-2-positive samples, 24 SARS-CoV-2 RNA-negative samples and 16 samples positive for other respiratory pathogens. The manufacturer's protocol was adapted to validate the antigen tests on transport media used for rRT-PCR in the authors' routine practice. The SD Biosensor RAD assay was implemented as a screening method for rapid diagnosis and targeted admission. FINDINGS: Sensitivity of the five RAD assays ranged from 88.9% to 100% for samples with cycle threshold values <26, and specificity ranged from 46.2% to 100%. During the implementation period, 4195 RAD tests were performed. Due to the rapid RAD result, 157 patients were transferred directly to the coronavirus disease 2019 (COVID-19) cohort ward instead of the regular ward (N=47) or the temporary COVID-19 ward (N=110). CONCLUSION: The SD Biosensor, Biotical and Panbio SARS-CoV-2 antigen tests showed acceptable overall performance, and identified the majority of contagious patients. In the context of high prevalence of SARS-CoV-2, RAD tests can be used as a rapid screening tool to guide infection prevention measures and aid targeted admission.

Travel history can make the difference.

Entamoeba histolytica infections are rare in developed countries such as Belgium. A 53-year-old female patient presented with 10 days of fever and mild persisting pain in the right hypochondriac despite 6 days of antibiotic therapy. The anamnesis further revealed that the patient was born in Colombia and visits her native country on a regular basis. An abdominal CT-scan demonstrated a large hepatic abscess of 10×8 cm. The diagnosis of Entamoeba histolytica- infection was confirmed with real-time PCR (RT-PCR) from the aspirated material of the abscess. Remarkably, a half year ago, this patient also presented to the gastro-enterology consultation with intermittent rectal bleeding, loose stools and abdominal discomfort. Rectosigmoidoscopy at that time showed sigmoiddiverticulosis and biopsies were taken. RT-PCR on this material was performed during this second episode and was positive for E. histolytica, confirming an episode of amoebic colitis a half year prior to the discovery of the liver abscess.

How to achieve accurate blood culture volumes: the BD BACTEC FX blood volume monitoring system as a measuring instrument and educational tool.

Collecting adequate volumes of blood in blood culture bottles is crucial for sensitive detection of bacteremia and fungemia. Tools enabling easy collection of data on the degree of blood culture bottle filling at different hospital departments are an important step toward quality measurement and improvement. In this study, we verified the accuracy of a software tool for the monitoring of blood culture bottle filling developed by Becton Dickinson, BD blood volume monitoring system (BVMS) that was adjusted for use on plastic BACTEC bottles, and evaluated its ease of use in routine practice. In total, 538 negative plastic BD BACTEC Plus Aerobic/F blood culture bottles collected in two secondary care hospitals in Belgium were included in the study. The BVMS software demonstrated good performance, with an acceptable mean difference of - 0.3 mL or - 4.0% between the mean volume estimated by BVMS and the mean weight-based volume. Data (mean blood volume and standard deviation) and figures (box-and-whisker and histogram plots) on blood culture bottle filling are easily acquired. They provide information on the current situation in a hospital (department) and can be used as a tool for quality improvement measurements and follow-up. Caution is required when interpreting BVMS results for hospital wards where a substantial amount of the bottles collected come from patients with hematocrit values < 30%. This study demonstrated that BVMS is a reliable and easy to use tool which facilitates monitoring and coordination of optimization of blood culture bottles filling by the clinical laboratory.

Epstein-Barr virus serology and PCR: conflicting results in an immunocompetent host. A case report and review of literature.

We present the case of a 27-year-old immunocompetent man who progressively developed a generalized lymphadenopathy and B symptoms. Results of Epstein-Barr virus (EBV) serology were suggestive for a past infection, but the EBV viral load in whole blood was high. Also, core needle biopsy of the largest lymph node showed an image which could fit an EBV-driven reactive lymphoproliferation. Despite the absence of an immune disorder, all medical evidence points to an EBV-driven lymphoproliferative proces. In immunocompetent patients, it seems extremely uncommon to detect a high EBV viral load in the absence of serological evidence of an acute EBV infection or reactivation. We reviewed literature on this topic and on the selection of the appropriate sample type for EBV PCR, as this is known to be a critical point. Serological testing for the diagnosis of EBV infection is the gold standard in immunocompetent patients. Measuring EBV viral load is only recommended when dealing with immunocompromised patients. Although extremely rare, this case report shows that there is a place for EBV PCR in certain situations in immunocompetent patients. Besides, there is still no consensus regarding the specimen of choice for the determination of the EBV viral load. The preferred specimen type seems to depend on the patient's underlying condition.