Performance Evaluation of the Siemens SARS-CoV-2 Total Antibody and IgG Antibody Test.

OBJECTIVE: In this study, the performance of 2 commercially available SARS-CoV-2 antibody assays is evaluated. METHODS: The Siemens SARS-CoV-2 Total (COV2T) and IgG (COV2G) antibody tests were evaluated on a Siemens Atellica IM1300 analyzer. Imprecision was assessed with the CLSI EP15 protocol using positive controls. Ninety control group specimens were analyzed for specificity, and 175 specimens from 58 patients with polymerase chain reaction-confirmed SARS-CoV-2 were measured for the sensitivity and kinetics of the antibody response. RESULTS: Within-run and total imprecision were acceptable for both assays. Both tests showed a specificity of 100%. Sensitivity earlier in the disease state was greater for the COV2T assay than for the COV2G assay, but sensitivity >14 days after onset of symptoms approached 100% for both. For all patients, antibody titers remained above the seroconversion cutoff for all follow-up specimens. CONCLUSION: This study shows acceptable performance for both the Siemens COV2T and COV2G test, although seroconversion occurs earlier with the COV2T test.

Flow cytometric analysis of platelet function to improve the recognition of thrombocytopathy.

INTRODUCTION: Light transmission aggregometry (LTA) is the gold standard for diagnosing bleeding disorders. Although LTA is laborious, requires large volumes of blood and is relatively insensitive to small changes in platelet function, there is still no competing alternative approach to replace LTA for the diagnosis of platelet bleeding disorders. MATERIALS AND METHODS: This study investigates the correlation between flow cytometry-based whole blood platelet activation test (WB-PACT) and LTA and whether WB-PACT is of additional value for the identification of bleeding disorders. In total, 161 patients with suspected bleeding diathesis were tested. RESULTS: A correlation of 0.41 between LTA and WB-PACT was found, and there was agreement between tests in 62% of cases (κ = 0.23). The WB-PACT is of additional value to LTA to detect platelet function disorders (PFD) as 10 patients with elevated bleeding score (BS) were detected with WB-PACT, 4 with LTA and 7 patients were positive with both tests. Interestingly, in contrast to LTA, WB-PACT has an additional option to detect VWF disfunctions. CONCLUSION: WB-PACT may have added value for the routine diagnostic work-up in patients who need to have platelet function tested.

Evaluation of the primary biliary cholangitis-related serologic profile in a large cohort of Belgian systemic sclerosis patients.

Background Systemic sclerosis (SSc) and primary biliary cholangitis (PBC) are autoimmune diseases that may occur concomitantly and are both strongly associated with disease-specific autoantibodies. This study investigated the prevalence and fine specificity of PBC-specific serology (PBC-Ab) and associations with the SSc-subtypes and SSc-specific antibodies as well as the association with cholestatic liver enzymes. Furthermore, three different techniques for the detection of PBC-Ab were compared. Methods Serum of 184 Belgian SSc patients with a known SSc-antibody profile, was analyzed for PBC-Ab (antimitochondrial antibodies [AMA], anti-Gp210, anti-Sp100 and anti-PML) using indirect immunofluorescence (IIF) analysis on human epithelioma-2000 (HEp-2000) cells (ANA-IIF, Immunoconcepts) and liver-kidney-stomach tissue sections (IIF-LKS) (Menarini), and a line immunoblot (LB) (EuroImmun). Alkaline phosphatase/γ-glutamyl transferase (ALP/GGT) were evaluated at time of first sampling (t0) and after 3 years of follow-up (t3). Results PBC-Ab were present in 13% of patients and significantly correlated with centromere antibodies (anti-CENP-B), but not correlated with the limited cutaneous SSc subgroup (lcSSc). The most frequent reactivities were AMA (11%, with 9% AMA-M2) and Sp-100 antibodies (5%), showing a major overlap. There was no relevant association between the presence of PBC-Ab and ALP or GGT elevation at t0 nor at t3. Detection of AMA with IIF-LKS is comparable to LB. ANA-IIF screening was less sensitive compared to LB. Conclusions A wide range of PBC-Ab is detectable in SSc in the absence of cholestatic liver enzyme elevations, even after 3 years of follow-up. However, as these antibodies may precede PBC-disease up to 10 years further prospective follow-up of our cohort will be necessary.

Evaluation of an automated algorithm for interpretation of lupus anticoagulant testing.

INTRODUCTION: Lupus anticoagulant (LAC) testing is a multistep procedure including screening, mixing, and confirmation tests. STA Coag Expert is a software module for STA R Max and STA Compact Max analyzers which includes an on-demand LAC algorithm, based on ISTH guidelines, for automatic interpretation, calculation, and launch of assays in LAC interpretation ("Stago coag algorithm"). MATERIALS AND METHODS: One hundred ninety four patient samples were analyzed in parallel and interpreted manually and automatically by LAC algorithms. LAC algorithms use identical flowcharts and cutoff values as in daily practice. Differently, it only uses index of circulating anticoagulant (ICA), whereas in routine also normalized ratios were assessed for interpretation of mixing tests. Interpretation of dRVVT and aPTT pathways and final conclusions were compared between both approaches. RESULTS: Compared to routine interpretation, LAC algorithm showed a sensitivity of 94% and a specificity of 100% for LAC detection, when discrepancies due to measured clotting times between both analyzers were excluded. Three false negatives were due to different interpretation of dRVVT mixing test. Discrepancies in interpretation of the aPTT mixing test (n = 11) did not result in discrepant final LAC result, all having negative confirmation tests. No false positives were observed. With LAC algorithm, hands-on time reduced from 200 to 80 minutes. CONCLUSION: The LAC algorithm of the STA Coag Expert shows good comparability to the manual interpretation of LAC and may be used to assist laboratories in automatic launching of additional tests and in interpretation of LAC according to ISTH guidelines. This way the STA Coag Expert LAC algorithm may improve interlaboratory and STA comparability of LAC results.

Diagnostic utility of the lymphoid screening tube supplemented with CD34 for Ogata score calculation in patients with peripheral cytopenia.

OBJECTIVES: The diagnosis of myelodysplastic syndrome (MDS) is not always straightforward in the absence of objective markers such as ringed sideroblasts, an excess of blasts or clonal cytogenetic abnormalities. Moreover, the lack of specificity of morphological dysplasia makes the differentiation between MDS and other causes of peripheral cytopenia difficult. The WHO 2016 classification of MDS recognizes multiparameter flow cytometry (MFC) as an adjuvant tool for MDS diagnosis. An easily applicable MFC protocol based on CD34 and CD45 is proposed by Ogata et al. Furthermore, in the diagnostic workup of patients with peripheral cytopenia, the integration of MFC by means of a Lymphoid Screening Tube (LST) is recommended by the EuroFlow™ consortium. The aim of this study was to investigate whether the LST, supplemented with CD34, can be used to calculate the Ogata score, thereby obviating the need to run different flow cytometric tubes. METHODS: Bone marrow samples from 108 patients with peripheral cytopenia were analyzed (MDS n = 32; non-MDS n = 76). The LST used in the present study was based on the tube designed by the EuroFlow™ consortium, but with addition of CD34 and without TCRγδ. RESULTS: Rather low sensitivities of 55% in low-grade MDS patients and 80% in high-grade MDS patients were observed. However, a high specificity of 92% was found in the non-MDS group. CONCLUSION: Besides screening for clonal lymphocytes, plasma cells and blasts, an LST supplemented with CD34 allows the calculation of the Ogata score as an adjuvant tool in the diagnostic workup of cytopenic patients suspected of MDS.

Evaluation of the CellaVision DM96 advanced RBC application for screening and follow-up of malaria infection.

CellaVision DM96 is a digital cell morphology system for automated classification of white and red blood cells. CellaVision Advanced RBC application (ARBCA) pre-classifies RBC in 21 categories, including parasitized RBC, and allows re-classification by the operator. In this study, the performance of the software for detection of malaria and calculation of parasitemia was evaluated and compared to microscopy (n=40). For CellaVision, both pre- and post-reclassification results were evaluated. Sensitivity was moderate, even post-reclassification (72%), due to low numbers of analyzed RBC and limited resolution of photographs. CellaVision results correlated with microscopy according to Passing-Bablok analysis, with slightly lower values for CellaVision. Within-run, between-run and inter-observer variability were acceptable. The low sensitivity of CellaVision ARBCA precludes its use as a screening technique for malaria. However, due to its good correlation with microscopy and short turn-around-times, it may be useful in follow-up of parasitemia. Larger studies are required to confirm these findings.

Surveillance of Endoscopes: Comparison of Different Sampling Techniques.

OBJECTIVE To compare different techniques of endoscope sampling to assess residual bacterial contamination. DESIGN Diagnostic study. SETTING The endoscopy unit of an 1,100-bed university hospital performing ~13,000 endoscopic procedures annually. METHODS In total, 4 sampling techniques, combining flushing fluid with or without a commercial endoscope brush, were compared in an endoscope model. Based on these results, sterile physiological saline flushing with or without PULL THRU brush was selected for evaluation on 40 flexible endoscopes by adenosine triphosphate (ATP) measurement and bacterial culture. Acceptance criteria from the French National guideline (<25 colony-forming units [CFU] per endoscope and absence of indicator microorganisms) were used as part of the evaluation. RESULTS On biofilm-coated PTFE tubes, physiological saline in combination with a PULL THRU brush generated higher mean ATP values (2,579 relative light units [RLU]) compared with saline alone (1,436 RLU; P=.047). In the endoscope samples, culture yield using saline plus the PULL THRU (mean, 43 CFU; range, 1-400 CFU) was significantly higher than that of saline alone (mean, 17 CFU; range, 0-500 CFU; P<.001). In samples obtained using the saline+PULL THRU brush method, ATP values of samples classified as unacceptable were significantly higher than those of samples classified as acceptable (P=.001). CONCLUSION Physiological saline flushing combined with PULL THRU brush to sample endoscopes generated higher ATP values and increased the yield of microbial surveillance culture. Consequently, the acceptance rate of endoscopes based on a defined CFU limit was significantly lower when the saline+PULL THRU method was used instead of saline alone. Infect Control Hosp Epidemiol 2017;38:1062-1069.