Rapid screening method for the detection of SARS-CoV-2 variants of concern.

BACKGROUND: Comprehensive and up-to-date monitoring of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOC) is crucial as these are characterized by their increased transmissibility, immune evasion and virulence. OBJECTIVES: To describe the wide-scale implementation of a reverse transcriptase polymerase chain reaction (RT-PCR) multiple variants assay with melting curve analysis as a routine procedure. STUDY DESIGN: We prospectively performed multiple variants RT-PCR on consecutive SARS-CoV-2 RT-PCR positive samples from patients, healthcare workers and nursing home residents from our hospital catchment area. This technique was implemented in our automated Roche FLOW system with a turn-around time of 6 h. RESULTS: Between February 1 and May 2, 2021, 989 samples were tested by the variant RT-PCR. Our method was validated by comparison of variant RT-PCR to whole genome sequencing testing. We observed an increase over time in the proportion of UK variant that became the dominant variant, and the concurrent emergence of the South-African and Brazilian variants. Prompt public health responses for infection control were possible because of this rapid screening method, resulting in early detection and reduction of unnoticed spread of VOC as early as possible. CONCLUSION: A variant RT-PCR with additional melting curve analyses is a feasible, rapid and efficient screening strategy that can be implemented in routine microbiological laboratories.

Comparison of the GeneFinderTM COVID-19 Plus RealAmp Kit on the sample-to-result Platform ELITe InGenius to the national reference method: An added value of N gene target detection?

BACKGROUND: Due to the emergence of the coronavirus disease 2019 (COVID-19) pandemic there is an urgent need for rapid and accurate testing on the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). OBJECTIVES: The aim of this study was to assess the diagnostic performance of the GeneFinderTMCOVID-19 Plus RealAmp Kit on the ELITe InGenius sample-to-result platform, which is a commercial nucleic acid amplification test (NAT) targeting genes of SARS-CoV-2. STUDY DESIGN: Patients were eligible between March 18 and May 27, 2020, when they had respiratory symptoms that were suspected for COVID-19. The InGenius platform was compared to routine in-house NAT that was validated according to the national reference. RESULTS: Of 128 randomly selected patients, 58 (45 %) tested positive and 55 (43 %) tested negative in both platforms. Sensitivity of the InGenius platform was 100 % (95 % confidence interval 94-100). In the remaining 15 (12 %) cases E and RdRp genes were not detected in both platforms but the nucleoprotein (N) gene was tested positive by the InGenius platform. All solitary N gene positive cases were confirmed by a N-gene specific in-house validated NAT, and most of these patients could also be considered positive based on other recently available COVID-19 positive respiratory samples or highly suspected radiological findings. CONCLUSION: The InGenius platform for SARS-CoV-2 detection has excellent sensitivity, is easy to use and provides fast results. The inclusion of the N gene as a third gene target may further increase sensitivity for the diagnosis of COVID-19 in comparison to the national reference method.

The Helicobacter hepaticus hefA gene is involved in resistance to amoxicillin.

BACKGROUND: Gastrointestinal infections with pathogenic Helicobacter species are commonly treated with combination therapies, which often include amoxicillin. Although this treatment is effective for eradication of Helicobacter pylori, the few existing reports are less clear about antibiotic susceptibility of other Helicobacter species. In this study we have determined the susceptibility of gastric and enterohepatic Helicobacter species to amoxicillin, and have investigated the mechanism of amoxicillin resistance in Helicobacter hepaticus. MATERIALS AND METHODS: The minimal inhibitory concentration (MIC) of antimicrobial compounds was determined by E-test and agar/broth dilution assays. The hefA gene of H. hepaticus was inactivated by insertion of a chloramphenicol resistance gene. Transcription was measured by quantitative real-time polymerase chain reaction. RESULTS: Three gastric Helicobacter species (H. pylori, H. mustelae, and H. acinonychis) were susceptible to amoxicillin (MIC < 0.25 mg/L). In contrast, three enterohepatic Helicobacter species (H. rappini, H. bilis, and H. hepaticus) were resistant to amoxicillin (MIC of 8, 16, and 6-64 mg/L, respectively). There was no detectable beta-lactamase activity in H. hepaticus, and inhibition of beta-lactamases did not change the MIC of amoxicillin of H. hepaticus. A H. hepaticus hefA (hh0224) mutant, encoding a TolC-component of a putative efflux system, resulted in loss of amoxicillin resistance (MIC 0.25 mg/L), and also resulted in increased sensitivity to bile acids. Finally, transcription of the hefA gene was not responsive to amoxicillin, but induced by bile acids. CONCLUSIONS: Rodents are frequently colonized by a variety of enterohepatic Helicobacter species, and this may affect their global health status and intestinal inflammatory responses. Animal facilities should have treatment strategies for Helicobacter infections, and hence resistance of enterohepatic Helicobacter species to amoxicillin should be considered when designing eradication programs.

Inverse nickel-responsive regulation of two urease enzymes in the gastric pathogen Helicobacter mustelae.

The acidic gastric environment of mammals can be chronically colonized by pathogenic Helicobacter species, which use the nickel-dependent urea-degrading enzyme urease to confer acid resistance. Nickel availability in the mammal host is low, being mostly restricted to vegetarian dietary sources, and thus Helicobacter species colonizing carnivores may be subjected to episodes of nickel deficiency and associated acid sensitivity. The aim of this study was to investigate how these Helicobacter species have adapted to the nickel-restricted diet of their carnivorous host. Three carnivore-colonizing Helicobacter species express a second functional urea-degrading urease enzyme (UreA2B2), which functions as adaptation to nickel deficiency. UreA2B2 was not detected in seven other Helicobacter species, and is in Helicobacter mustelae only expressed in nickel-restricted conditions, and its expression was higher in iron-rich conditions. In contrast to the standard urease UreAB, UreA2B2 does not require activation by urease or hydrogenase accessory proteins, which mediate nickel incorporation into these enzymes. Activity of either UreAB or UreA2B2 urease allowed survival of a severe acid shock in the presence of urea, demonstrating a functional role for UreA2B2 in acid resistance. Pathogens often express colonization factors which are adapted to their host. The UreA2B2 urease could represent an example of pathogen adaptation to the specifics of the diet of their carnivorous host, rather than to the host itself.