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Aims A novel method has been developed that allows successful differentiation between Clostridium difficile culture-positive and culture-negative stool samples based on volatile organic compound ( VOC) evolution and detection by headspace solid-phase microextraction coupled with gas chromatography mass spectrometry ( HS- SPME- GC- MS). Methods and Results The method is based on the activation of p-hydroxyphenylacetate decarboxylase produced by Cl. difficile and the detection of a specific VOC, that is 2-fluoro-4-methylphenol from an enzyme substrate. In addition, other VOCs were good indicators for Cl. difficile, that is isocaproic acid and p-cresol, although they could not be used alone for identification purposes. One hundred stool samples were tested, of which 77 were positive by culture. Detection using HS- SPME- GC- MS allowed confirmation of the presence of Cl. difficile within 18 h with a sensitivity and specificity of 83·1 and 100%, respectively. Conclusions It is recommended that this new approach could be used alongside conventional methods for Cl. difficile detection, including toxin detection methods, which would allow any false-negative results to be eliminated. Significance and Impact of the Study The ability to identify Cl. difficile-positive stool samples by the analysis of VOCs could allow the development of a VOC detection device which could allow rapid diagnosis of disease and hence prompt treatment with appropriate antibiotics. [ABSTRACT FROM AUTHOR]

Background and Objectives The determination of foetal RHD genotype using foetal DNA contained in the maternal circulation is increasingly used to manage pregnancies at risk of haemolytic disease of the foetus and newborn (HDFN) caused by maternal anti-D. The test is becoming increasingly reliable, and routine clinical services have been established in some centres. However, laboratories currently have no reference materials with which to determine the performance of their tests. This report describes the production and evaluation of a freeze-dried preparation of human plasma, code 07/222, containing RHD and SRY sequences which can be used as a minimum sensitivity reagent. Materials and Methods RhD-positive male plasma was diluted in an excess of RhD-negative female plasma, and 1 ml aliquots were freeze-dried in glass ampoules. To characterise the material, 19 laboratories took part in an international collaborative study. The participants evaluated dilutions of the material using their in-house routine assays and recorded the highest dilution where the genes could be detected. Results When diluted 1 in 2, most laboratories were able to detect the presence of RHD and SRY sequences in the material and the participants agreed that this was an appropriate level to set as the minimum sensitivity required. Conclusions In October 2010, the WHO Expert Committee on Biological Standardization approved the material 07/222 as an International Reference Reagent for the detection of RHD and SRY DNA in plasma. [ABSTRACT FROM AUTHOR]