ObjectivesSerological assays for detection of SARS-CoV-2 antibodies are increasingly used during the COVID-19 pandemic caused by the SARS-Coronavirus-2. Here we evaluated the analytical and clinical performance of three commercially available SARS-CoV-2 antibody assays.MethodsA total of 186 samples from 58 patients with PCR-confirmed COVID-19 infection were measured using SARS-CoV-2 antibody assays by Siemens Healthineers, Roche Diagnostics and Euroimmun. Additionally, 123 control samples, including samples collected before December 2019 and samples with potential cross-reactive antibodies were analyzed. Diagnostic specificity, sensitivity, agreement between assays and ROC curve-derived optimized thresholds were determined. Furthermore, intra- and inter-assay precision and the potential impact of interfering substances were investigated.ResultsSARS-CoV-2 antibody assays by Siemens and Roche showed 100% specificity. The Euroimmun assay had 98 and 100% specificity, when borderline results are considered as positive or negative, respectively. Diagnostic sensitivity for samples collected ≥14 days after PCR-positivity was 97.0, 89.4 and 95.5% using the Siemens, Roche and Euroimmun assay, respectively. Sensitivity of the Roche assay can be increased using an optimized cut-off index (0.095). However, a simultaneous decrease in specificity (98.4%) was observed. Siemens showed 95.8 and 95.5% overall agreement with results of Euroimmun and Roche assay, respectively. Euroimmun and Roche assay exhibited 92.6% overall agreement. Discordant results were observed in three COVID-19 patients and in one COVID-19 patient none of the investigated assays detected antibodies.ConclusionsThe investigated assays were highly specific and sensitive in detecting SARS-CoV-2 antibodies in samples obtained ≥14 days after PCR-confirmed infection. Discordant results need to be investigated in further studies.

S. Harbarth). y Other members of the MODERN WP2 study group are listed in the study group section. Contents lists available at ScienceDirect Clinical Microbiology and Infection j o u r n a l h o m e p a g e : w w w . c l i n i c a l m i c r o b i o l o g y a n d i n f e c t i o n . c o m

on behalf of the MODERN WP3 study group, Populations of extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae are different in human-polluted environment and food items: A multicentre European study,

Background Carbapenem-resistant Pseudomonas aeruginosa strains are on the rise worldwide. This study characterized clinical isolates of P. aeruginosa from three Nigerian hospitals for carbapenem resistance. Methods Strains isolated from wounds (n = 88), urine/catheter tips (n = 25), sputum/tracheotomy aspirates (n = 5), ear swabs (n = 4) and vaginal swabs (n = 1) were identified by MALDI-TOF and antibiotic susceptibility testing was performed using the VITEK 2 system. The genomic DNA of each isolate was subject to sequencing using Illumina and Oxford nanopore technology. Bioinformatics analyses were performed to detect antimicrobial resistance genes, clonal affiliations and phylogenetic relations of 123 non-duplicate P. aeruginosa isolates, whereas assembly of the nanopore reads using the plasmIDent pipeline enabled the identification of plasmids. Results Forty-three percent of the isolates were resistant to all antibiotic categories tested. More than 40% of the isolates were resistant to the carbapenems imipenem and/or meropenem (39% and 44%, respectively). Among the meropenem-resistant isolates, 48 (89%) carried at least one carbapenemase gene. The predominant one was blaNDM-1 (n = 34), which conferred resistance to all five antibiotic categories and highly increased the MICs of both meropenem and imipenem. The other recurrent carbapenemase genes were blaVIM-2 (n = 4), and blaVIM-5-like (n = 11), which co-existed with blaNDM-1 in two isolates. Conclusions The study revealed a high rate of carbapenem resistance and conjugative, broad host range plasmids carrying carbapenemase-encoding genes, especially the NDM-1 type, among isolates of P. aeruginosa. This may forebode the emergency of ubiquitous carbapenem resistance urging the implementation of infection control and antimicrobial stewardship strategies in Nigerian hospitals.