Background: Due to the steadily rising case numbers of SARS-CoV-2 infections worldwide, there is an increasing need for reliable rapid diagnostic devices in addition to existing gold standard PCR methods. Actually, public attention is focused on antigen assays including lateral flow tests (LFTs) as a diagnostic alternative. Therefore, different LFTs were analyzed regarding their performance in a clinical setting. Material and Methods: A pilot sample panel of 13 bronchoalveolar fluids (BALFs) and 60 throat washing (TW) samples with confirmed PCR results, as well as eight throat washes invalid by PCR, were tested with the BIOCREDIT test (RapiGEN), the Panbio^TM assay (Abbott), and the SARS-CoV-2 rapid antigen test (Roche). Conclusion: The analyzed antigen test showed an interassay correlation of 27.4%, with overall specificities ranging from 19.4% to 87.1%, while sensitivities of the respective tests ranged between 33.3% and 88.1%. Because these assays did not entirely meet all high expectations, their benefit has to be carefully evaluated for the respective test strategy and setting.

A case of severe diarrhoea associated with synergistic human bocavirus type 1 (HBoV) and human herpes virus type 6 (HHV6) is reported. The case supports the hypotheses that HBoV infection under clinical conditions may depend on helper viruses, or that HBoV replicates by a mechanism that is atypical for parvoviruses, or that HBoV infection can be specifically treated with cidofovir.

Non-pneumonia Pneumocystis jirovecii colonization is thought to occur frequently in immunocompetent individuals. The aim was to analyze if P. jirovecii low-titer detections have more impact than just colonization. From our total cohort of patients for which P. jirovecii testing by qPCR was requested, we selected exclusively those that were fully immunocompetent. Patients were defined as fully immunocompetent if they did not receive immunosuppressive therapy, displayed regular antibody titers, and did not suffer from acquired, inherited or autoimmune diseases. Only those patients with complete medical records available were included. A retrospective analysis identified patients with P. jirovecii colonization and successful antibiotic therapy in response to laboratory pathogen detection. We identified 30 fully immunocompetent patients with P. jirovecii colonization suspected to suffer from infection with the pathogen, but with milder symptoms than pneumonia. All patients were successfully treated with cotrimoxazole against P. jirovecii and resolved from chronic cough and recurrent pulmonary infections. The fact that all patients displayed recovery from their clinical symptoms gives raise to the hypothesis that P. jirovecii infections may also occur in immunocompetent patients but with milder symptoms.

Due to the currently increasing case numbers of SARS-CoV-2 infections worldwide there is an increasing need for rapid diagnostic devices in addition to existing PCR-capacities. Therefore, rapid antigen assays including lateral flow assays are discussed as an alternative method. In comparison to an established RT-PCR protocol, however the novel lateral flow assay unfortunately lowered the expectations set in these assays.

In limelight of the ongoing pandemic SARS-CoV-2 testing is critical for the diagnosis of infected patients, contact-tracing and mitigating the transmission. Diagnostic laboratories are expected to provide appropriate testing with maximum accuracy. Real-time reverse transcriptase PCR (RT-PCR) is the diagnostic standard yet many commercial diagnostic kits have become available. However, only a handful of studies have reviewed their performance in clinical settings. The aim of this study was to compare the performance of the overall analytical matrix including the extraction kit (BD MAX, Promega, Qiagen), the PCR instrument (Agilent Mx3005P, BD MAX, Qiagen Rotor-Gene, Roche Cobas z 480) and the RT-PCR assay (Altona Diagnostics, CerTest Biotec, R-Biopharm AG) using predefined samples from proficiency testing organizers. The greatest difference of the Ct values between the matrices was 9 cycles. One borderline sample could not be detected by 3 out of 12 analytical matrices and yielded a false negative result. We therefore conclude that diagnostic laboratories should take the complete analytical matrix in addition to the performance values published by the manufacturer for a respective RT-PCR kit into account. With limited resources laboratories have to validate a wide range of kits to determine appropriate analytical matrices for detecting SARS-CoV-2 reliably. The interpretation of clinical results has to be adapted accordingly.