Evaluation of the fully automated, sample-to-result Seegene STARlet-AIOS platform for detection of SARS-CoV-2, influenza virus A, influenza virus B, and RSV.

Early, accurate, and bulk detection of respiratory pathogens is essential for patient management and infection control. STARlet-All-in-One System (AIOS) (Seegene) is a new, fully automated, sample-to-result, molecular diagnostic platform. This study describes the first evaluation of STARlet-AIOS, by testing the Allplex™ SARS-CoV-2 (AS) and Allplex™ SARS-CoV-2/FluA/FluB/RSV combination (AC) assays in comparison to the SARS-CoV-2 assays used at our institute. Over a 3-week period, all naso-/oropharyngeal specimens tested for SARS-CoV-2 using either GeneXpert, Panther, or in-house developed test (LDT) were tested on the AIOS using the AS or AC assays. In addition, retrospective cohorts of specimens containing SARS-CoV-2, influenza virus A, influenza virus B, and RSV were tested. Discrepant results were re-tested with another assay used in this study. Hands-on time (HOT) and turn-around time (TAT) of the different systems were monitored and compared. A total of 738 specimens were tested on the AIOS using the AS assay. In addition, 210 specimens were tested using the AC assay. Overall agreement for SARS-CoV-2 detection was established as 98.5% and 95.2% for the AS and AC assay, respectively. Retrospective testing revealed high agreements for all targets, except for influenza virus A (agreement of 87.5%). HOT of the system was comparable to the HOT of GeneXpert and Panther and TAT comparable to Panther and LDT. The AIOS proved to be a robust sample-to-result system with low HOT and moderate TAT. This study showed reliable detection of SARS-CoV-2, influenza virus B, and RSV, whereas detection of influenza virus A using the AC assay appeared to be suboptimal.

Low prevalence of SARS-CoV-2 in plasma of COVID-19 patients presenting to the emergency department.

Correct and reliable identification of SARS-CoV-2 in COVID-19 suspected patients is essential for diagnosis. Respiratory samples should always be tested with real-time PCR for SARS-CoV-2. In addition, blood samples have been tested, but without consistent results and therefore the added value of this sample type is unknown. The aim of this study was to determine the prevalence of SARS-CoV-2 by real-time PCR in blood samples obtained from PCR-proven COVID-19 patients and in addition to elaborate on the potential use of blood for diagnostics. In this single center study, blood samples drawn from patients at the emergency department with proven COVID-19 infection based on a positive SARS-CoV-2 PCR in respiratory samples were tested for the presence of SARS-CoV-2. Samples from 118 patients were selected, of which 102 could be included in the study (median age was 65 (IQR 10), 65.7 % men). In six (5.9 %) of the tested samples, SARS-CoV-2 was identified by real-time PCR. In conclusion, SARS-CoV-2 can be detected by real-time PCR in plasma samples from patients with proven COVID-19, but only in a minority of the patients. Plasma should therefore not be used as primary sample in an acute phase setting to identify SARS-CoV-2 infection. These findings are important to complete the knowledge on possible sample types to test to diagnose COVID-19.

Detection of parvovirus B19 DNA in blood: Viruses or DNA remnants?

BACKGROUND: Parvovirus B19 (B19V) DNA can be detected in blood over a long period after acute infection. Several reports associate the presence of B19V DNA with disease, irrespective of timing of the initial B19V infection. OBJECTIVES: This study aims to analyze the properties of B19V DNA in blood, differentiating between bare, non-infectious strands of DNA and B19V DNA in viable virions. STUDY DESIGN: Ten blood donors with asymptomatic acute B19V infection were followed and sampled up to 22 months after infection. The samples were treated with and without an endonuclease and tested for B19V DNA, to distinguish between DNA in virions and naked DNA. RESULTS: In the acute phase of infection, high levels of B19V DNA were detected, concurrent with B19V IgM antibodies. B19V DNA apparently was encapsidated, as indicated by resistance to endonuclease degradation. Subsequently, B19V DNA remained detectable for more than one year in all donors at low levels (<105 IU/mL). Approximately 150days after infection B19V DNA became degradable by an endonuclease, indicating that this concerned naked DNA. In some donors a second endonuclease-resistant peak occurred. DISCUSSION: Detection of B19V DNA in blood by PCR does not necessarily imply that B19V replication takes place and that infectious B19V virions are present. We propose that remnant B19V DNA strands can be released from tissues without active replication. This finding urges to reconsider an assumed role of B19V infection mainly based on B19V DNA detection in blood, a much debated subject in clinical syndromes such as myocarditis and arthritis.

The effect of discontinuation of postmilking teat disinfection in low somatic cell count herds. I. Incidence of clinical mastitis.

Results are described of a split-udder trial on the effect of discontinuation of postmilking teat disinfection on the incidence of clinical mastitis in seven dairy herds with a low bulk milk somatic cell count and a high incidence of clinical mastitis. Overall incidence of clinical mastitis was non-significantly lower (18%), whereas the incidence of the most prevalent pathogen associated with clinical mastitis, Escherichia coli, was significantly lower in quarters for which postmilking teat disinfection was discontinued. We concluded that discontinuation of postmilking teat disinfection may decrease the incidence of clinical Escherichia coli mastitis in herds for which standard mastitis prevention measures are executed adequately, bulk milk somatic cell count is low, and incidence of clinical mastitis is high. However, because an increase in intramammary infections with contagious pathogens may occur, care is recommended when advising discontinuation of postmilking teat disinfection.

The effect of discontinuation of postmilking teat disinfection in low somatic cell count herds. II. Dynamics of intramammary infections.

Results of a 20 month split-udder trial on the effect of discontinuation of postmilking teat disinfection on intramammary infections (IMI) with major and minor pathogens in seven dairy herds with a low somatic cell count are described. The incidence of Escherichia coli IMI was found to be significantly lower, whereas the incidence of IMI with Staphylococcus aureus and minor pathogens was significantly higher in quarters for which postmilking teat disinfection was discontinued than in disinfected quarters. It was concluded that discontinuation of postmilking teat disinfection decreased the incidence of E. coli IMI, accompanied by a, from a practical point of view, acceptable rise in somatic cell count. However, the possible increase in the incidence of S. aureus IMI calls for careful monitoring of the dynamics of IMI with contagious pathogens, when postmilking teat disinfection is discontinued in an attempt to reduce E. coli mastitis.