A rapid, sensitive and specific analysis of food samples determining wheat contamination was established using polymerase chain reaction (PCR) technology. First, primers specific for highly conserved eukaryote DNA sequences were used to prove isolated nucleic acid substrate accessibility to PCR amplification. Subsequently, a highly repetitive and specific genomic wheat DNA segment was amplified by PCR for wheat detection. This assay was tested with 35 different food samples ranging from bakery additives to heated and processed food samples. In addition, the PCR method was compared to an immunochemical assay that detected the wheat protein component gliadin. Combination of both assays allowed a detailed characterization of wheat contamination. Hence, wheat flour contamination could be distinguished from gliadin used as a carrier for spices as well as from wheat starch addition.

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The polymerase chain reaction was used to obtain randomly-amplified polymorphic DNA (RAPD) profiles from Listeria spp. and enterobacteria. Eleven different oligonucleotides were evaluated. Only one, HR4 (19mer), generated reproducible and specific profiles for Listeria spp., while results for enterobacteria were controversial. A total of 57 different Listeria strains were subjected to the RAPD analysis and 27 different profiles were recognized. RAPD typing allowed strains of the same serotype to be distinguished but the same profile was obtained from different serotypes of L. monocytogenes in three cases and in one case two different serotypes of L. innocua yielded the same profile. RAPD-typing with HR4 allowed L. monocytogenes contamination in several food outlets to be traced back to a food processing plant. In additional experiments, the general utility of this RAPD system in typing Yersinia enterocolitica, verotoxigenic Escherichia coli and Salmonella enteritidis was evaluated.

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Although SARS-CoV-2 antibody assays have been found to provide valid results in EDTA-anticoagulated whole blood, so far, they have not demonstrated that antibody levels in whole blood originating from capillary blood samples are comparable to antibody levels measured in blood from a venous origin. Here, blood is drawn simultaneously by capillary and venous blood sampling. Antibody titers are determined by an assay employing electrochemiluminescence (ECLIA) and SARS-CoV-2 total immunoglobulins are detected with specificity directed against the nucleocapsid antigen. Six individuals with confirmed COVID-19 and six individuals without COVID-19 are analyzed. Antibody titers in capillary venous whole blood did not show significant differences, and when corrected for hematocrit, they did not differ from the results obtained from serum. In conclusion, capillary sampled EDTA-anticoagulated whole blood seems to be an attractive alternative matrix for the evaluation of SARS-CoV-2 antibodies when employing ECLIA for detecting total antibodies directed against nucleocapsid antibodies.