Fast diagnostic tools are becoming a hot topic in microbiology, especially in the case of septic patients. Therefore, we attempted to develop a fast, inexpensive, accurate and easy method to identify bacteria and perform an antibiotic susceptibility test directly on positive blood cultures that could be used in a routine laboratory. A procedure based on centrifugation and washing steps was performed on 110 non-duplicated (including nine seeded) positive blood culture bottles. Direct identification (DID) and antimicrobial susceptibility testing (AST) was conducted on the pellet with the MALDI Biotyper and Phoenix, respectively. Identification (ID) to the species level was correct in 44/45 (97%) cases for Gram-negative bacteria and 44/56 (79%) cases for Gram-positive bacteria. In total, 98.9% of the AST results were identical to the routine laboratory result. No very major errors, four major errors and eight minor errors were detected. A reliable identification and a high AST agreement were obtained from blood cultures seeded with multi-resistant bacteria. We simulated the timeline of DID and demonstrated an identification and AST result within 24 h using Escherichia coli- and Staphylococcus aureus-positive blood cultures as examples. We developed an easy, fast and cheap method to generate reliable ID and AST results. Moreover, this method may be used to obtain results within 24 h after incubating the blood culture bottles in the microbiology lab.

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Essentials Limited data are available of freeze‐thaw effect on anticardiolipin and anti‐beta2‐glycoprotein I antibodies.Patient samples with antibody titer over a broad range were analyzed in a standardized freezing‐thawing scheme.aCL and aβ2GPI IgG and IgM titers are stable over time and after repeated freeze‐thawing.Repeated use of samples facilitates routine work‐out and use of samples for scientific purposes. BackgroundPre‐analytical factors, like freeze‐thaw cycles (FTC), can potentially affect results and clinical interpretation. According to the SSC‐ISTH recommendations for antiphospholipid antibodies (aPL) testing, additional FTC should be avoided to maintain the best performance. Patient samples are often analyzed in batch and having one frozen sample aliquot for all aPL tests, that may hamper daily routine work‐out. To use them for study or method validation purpose, sample storage in bio banks is often done in one aliquot also triggering the need for several FTC to be able to use them in different scientific projects. Taking into account the limited scientific literature, the strict guidelines and the potential benefits of repeated FTC we evaluated this pre‐analytical factor.ObjectivesEvaluating the effect of repeated FTC on anticardiolipin (aCL) IgM/IgG and anti‐beta‐2 glycoprotein 1 (aβ2GPI) IgM/IgG antibody titer.Patient/Methods42 patient plasmas that were not thawed before, were retrieved from the routine archive (−80°C). All aliquots were analyzed on five consecutive days with an additional, standardized FTC every day. Mann‐Withney tests for statistical differences and a concordance correlation coefficient (CCC) were calculated between the first and following FTC.Results and ConclusionFor all four aPL no statistical difference or degradation from positive to negative was seen, even after five FTC. The CCC between the first and fifth FTC were between 0.98 and 1 for all four aPL. aCL IgM/IgG and aβ2GPI IgM/IgG antibody titer, over a broad titer range, are stable over time and after repeated FTC.

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.

Background Detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern associated with immune escape is important to safeguard vaccination efficacy. We describe the potential of delayed N gene amplification in the Allplex SARS-CoV-2 Assay (Seegene) for screening of the B.1.351 (20H/501.V2, variant of concern 2 [VOC.V2], South African SARS-CoV-2 variant) lineage. Methods In a study cohort of 397 consecutive polymerase chain reaction–positive samples genotyped by whole-genome sequencing, amplification curves of E/N/S-RdRP targets indicated delayed  N vs E gene amplification characteristic of B.1.351. Logistic regression was used to calculate a VOC.V2 probability score that was evaluated as a separate screening test in an independent validation cohort vs sequencing. Results B.1.351 showed a proportionally delayed amplification of the  N vs E gene. In logistic regression, only N and E gene cycle thresholds independently contributed to B.1.351 prediction, allowing calculation of a VOC.V2 probability score with an area under the curve of 0.94. At an optimal dichotomous cutoff point of 0.12, the VOC.V2 probability score achieved 98.7% sensitivity at 79.9% specificity, resulting in a negative predictive value (NPV) of 99.6% and a positive predictive value of 54.6%. The probability of B.1.351 increased with an increasing VOC.V2 probability score, achieving a likelihood ratio of 12.01 above 0.5. A near-maximal NPV was confirmed in 153 consecutive validation samples. Conclusions Delayed N vs E gene amplification in the Allplex SARS-CoV-2 Assay can be used for fast and highly sensitive screening of B.1.351.