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Rapid diagnosis of tuberculosis (TB) and antibiotic resistances are imperative to initiate effective treatment and to stop transmission of the disease. A new generation of more sensitive, automated molecular TB diagnostic tests has been recently launched giving microbiologists more choice between several assays with the potential to detect resistance markers for rifampicin and isoniazid. In this study, we determined analytical sensitivities as 95% limits of detection (LoD 95 ) for Xpert MTB/Rif Ultra (XP-Ultra) and BD-MAX MDR-TB (BD-MAX) as two representatives of the new test generation, in comparison to the conventional Fluoro-Type MTB (FT-MTB). Test matrices used were physiological saline solution, human and a mucin-based artificial sputum (MUCAS) each spiked with Mycobacterium tuberculosis in declining culture-and qPCR-controlled concentrations. With BD-MAX, XP-Ultra, and FT-MTB, we measured LoD 95 TB values of 2.1 cfu/ml (CI 95% : 0.9-23.3), 3.1 cfu/ml (CI 95% : 1.2-88.9), and 52.1 cfu/ml (CI 95% : 16.7-664.4) in human sputum; of 6.3 cfu/ml (CI 95% : 2.9-31.8), 1.5 cfu/ml (CI 95% : 0.7-5.0), and 30.4 cfu/ml (CI 95% : 17.4-60.7) in MUCAS; and of 2.3 cfu/ml (CI 95% : 1.1-12.0), 11.5 cfu/ml (CI 95% : 5.6-47.3), and 129.1 cfu/ml (CI 95% : 82.8-273.8) in saline solution, respectively. LoD 95 of resistance markers were 9 to 48 times higher compared to LoD 95 TB . BD-MAX and XP-Ultra have an equal and significantly increased analytical sensitivity compared to conventional tests. MUCAS resembled human sputum, while both yielded significantly different results than normal saline. MUCAS proved to be suitable for quality control of PCR assays for TB diagnostics.

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A commercially available PCR kit (AnDiaTec Salmonella sp. PCR-ELISA) was developed and evaluated for the detection of Salmonella sp. in food samples. The test is based on PCR amplification and hybridization of the amplified DNA to a microtiter plate followed by the detection of PCR product in the manner of an enzyme-linked immunosorbent assay test. The sensitivity and specificity were evaluated first with Salmonella pure cultures and artificially contaminated food samples, including food types for which an inhibition of the PCR reaction was expected. Both experiments proved a very good sensitivity, specificity, and reliability of the test with a very broad range of food types. In a second evaluation study, more than 1,100 food samples of different types were tested in parallel with the PCR method and with the International Standardization Organization 6579 bacteriological reference method. The results of this evaluation study and the results from other experiments on dilutions of artificially contaminated food samples led to the establishment of a positive-negative cutoff value (optical density at 450 nm of more than 0.9) with respect to the conventional bacteriological method. Using this positive-negative cutoff, 98% agreement to the bacteriological method was obtained.

Objective: Most of the PCR-based assays for the detection of adenoviruses require gel electrophoresis for resolution, which is time- and work-consuming and interpretation difficulties often occur. Therefore our objective was to develop and evaluate a PCR-ELISA for broad detection of adenoviruses, that is easy to perform and leads to an increase of specificity in virus detection. Methods: A total of 64 fecal specimens from patients with acute gastroenteritis, previously tested negative for other viruses than adenovirus and for bacterial pathogens, were tested for adenovirus in parallel with an Antigen-ELISA, virus isolation in cell culture, with a previously published hybridization-based PCR and our newly developed semi-nested PCR-ELISA. Results: The new PCR-ELISA turned out to be the best method with 26 samples positive for adenovirus. Of these, 22 became positive by Ag-ELISA, 19 by virus isolation in cell culture and only 14 by the previously published hybridization-based PCR. Conclusion: The semi-nested PCR-ELISA is a sensitive, reliable and rapid method for the detection of enteric adenoviruses from fecal samples.

fecal samples using the liquid culture. Using fecal PCR, we revealed 43 positive samples of which 39 also tested positive in the liquid culture, revealing MAP-positive cows in all 3 herds. The fecal PCR procedure allows rapid detection of MAP-specific DNA with 74% of the sensitivity of liquid culture. For the purpose of testing with maximal sensitivity, cultivation in liquid medium is recommended. Cultivation of MAP in liquid medium M7H9C means a significant time gain in comparison to cultivation on solid media, which requires twice as much time. Thus, this testing fits within the 6-to 8-wk dry period of gravid cows and provides test results before calving, a prerequisite to prevent fecal-oral transmission to newborn calves.