The global COVID-19 pandemic has resulted in a worldwide shortage of viral transport media and raised questions about specimen stability. The objective of this study was to determine the stability of SARS-CoV-2 virus RNA in specimen transport media under various storage conditions. Transport medium tested included: VCM, UTM®-RT, ESwab™, M4 and saline (0.9% NaCl). Specimen types tested included Nasopharyngeal/Oropharyngeal (NP/OP) swabs in the above transport media, bronchoalveolar lavage (BAL) and Sputum. A high-titer SARS-CoV-2 remnant patient specimen was spiked into pooled SARS-CoV-2 RNA-negative specimen remnants for the various media types. Aliquots of samples were stored at 18°C to 25°C, 2°C to 8°C and -10°C to -30°C and then tested at time points up to 14 days. Specimens consistently yielded amplifiable RNA with mean Ct differences of <3 over the various conditions assayed, thus supporting the use and transport of alternative collection media and specimen types under a variety of temperature storage conditions.
A total of 1200 serum samples that were tested for SARS-CoV-2 IgG antibody using the Abbott Architect immunoassay targeting the nucleocapsid protein were run in 3 SARS-CoV-2 IgG immunoassays targeting spike proteins (DiaSorin Liaison, Ortho VITROS, and Euroimmun). Consensus-positive and consensus-negative interpretations were defined as qualitative agreement in at least 3 of the 4 assays. Agreement of the 4 individual assays with a consensus-negative interpretation (N=610) ranged from 96.7% to 100%, and agreement with a consensus-positive interpretation (N=584) ranged from 94.3% to 100%. Laboratory-developed inhibition assays were utilized to evaluate 49 consensus-negative samples positive in only one assay; true-positive reactivity was confirmed in only 2 of these 49 (4%) samples. These findings demonstrate very high levels of agreement among 4 SARS-CoV-2 IgG assays authorized for emergency use, regardless of antigen target or assay format. Although false-positive reactivity was identified, its occurrence was rare (no more than 1.7% of samples for a given assay).
Since first reported in the Americas in December 2013, chikungunya virus (CHIKV) infections have been documented in travelers returning from the Caribbean, with many cases identified by CHIKV antibody and/or RNA testing at our laboratory. We used our large data set to characterize the relationship between antibody titers and RNA detection and to estimate IgM persistence. CHIKV RNA was measured by nucleic acid amplification and CHIKV IgG/IgM by indirect immunofluorescence. Of the 1,306 samples submitted for RNA testing in January through September 2014, 393 (30%) were positive; for 166 RNA-positive samples, CHIKV antibody testing was also ordered, and 84% were antibody negative. Of the 6,971 sera submitted for antibody testing in January through September 2014, 1,811 (26%) were IgM positive; 1,461 IgM positives (81%) were also IgG positive. The relationship between the CHIKV antibody titers and RNA detection was evaluated using 376 IgM-positive samples (138 with RNA testing ordered and 238 deidentified and tested for RNA). RNA detection showed no significant association with the IgM titer but was inversely related to the IgG titer; 63% of the IgG negative sera were RNA positive, compared to 36% of sera with low IgG titers (1:10 to 1:80) and 16% with IgG titers of >1:160. Using second-sample results from 62 seroconverters, we estimated that CHIKV IgM persists for 110 days (95% confidence interval, 78 to 150 days) after the initial antibody-negative sample. These findings indicate that (i) RNA detection is more sensitive than antibody detection early in CHIKV infection, (ii) in the absence of RNA results, the IgG titer of the IgM-positive samples may be a useful surrogate for viremia, and (iii) CHIKV IgM persists for approximately 4 months after symptom onset. C hikungunya virus (CHIKV) is an alphavirus transmitted from one person to another via mosquitos of the genus Aedes (1-3). Nearly all individuals infected with CHIKV become symptomatic, typically exhibiting fever, rash, and debilitating arthralgia (1-3). Most infected individuals show complete recovery within a few weeks; however, 15 to 60% of patients develop chronic arthralgia, which in turn can lead to arthritic joint damage (2, 4-7). Intrapartum mother-to-child transmission has been documented, with serious neurologic and hemorrhagic complications observed in affected infants (8).Since CHIKV was first identified in 1953 (9), there have been multiple epidemics of CHIKV infections throughout Africa and Asia (2). A particularly large CHIKV outbreak began in eastern Africa in late 2004 and then spread to Indian Ocean islands, India, and southeast Asia over the next 2 years. Estimates suggest that nearly 2 million people became infected during this outbreak (2, 10-15).Because the mosquito vectors for CHIKV transmission are present in tropical and temperate regions worldwide and recently infected travelers moving between areas where CHIKV is endemic and not endemic exhibit high levels of viremia (16), epidemiologists have warned that CHIKV could move into new g...
The objective of this study was to provide real-world clinical laboratory-based data to supplement Centers for Disease Control and Prevention (CDC) reporting of Q fever. We analysed titre results of specimens submitted to a large US clinical laboratory for Coxiella burnetii IgG antibody testing from 2010 through 2016. Presumptive Q fever was defined as acute (phase II IgG titre ⩾1:128, phase I titre <1:1024) or chronic (phase I IgG titre ⩾1:1024), based on the results from a single serum specimen. During 2010-2016, an average of 328 presumptive acute Q fever cases were identified at Quest each year, nearly three times the annual average reported to the CDC (122). During the same period, the number of chronic cases identified annually at Quest Diagnostics (34) was similar to that reported to the CDC (29). These findings suggest that CDC data may underestimate the incidence of acute Q fever.
The Simplexa™ Group A Strep Direct assay is intended for use on the Integrated Cycler for detection of Group A Streptococcus (GAS) directly from throat swabs that have not undergone nucleic acid extraction. A prospective study of 1352 samples in 4 geographically diverse sites showed an overall prevalence of GAS of 15.4%. The assay demonstrated 97.4% sensitivity and 95.2% specificity versus culture. The positive predictive value compared to culture was 72.7%. However, 46 out of 57 discrepant samples were Group A Strep positive when tested using a bi-directional sequencing method illustrating the increased sensitivity of the assay compared to culture for detection of GAS. Rapid and accurate diagnosis of GAS allows for timely treatment to decrease complications of this prevalent organism that continues to cause substantial morbidity and mortality worldwide.
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