No abstract

Exhaled breath condensate (EBC) describes any sample collected by cooling exhaled breath. Because the method of condensate collection is simple, non-invasive, repeatable and does not necessarily require patient cooperation, EBC is not only an interesting, but also challenging, biological sample. Despite a period of EBC research lasting for more than 15 years, there are still many open questions with respect to EBC collection and analysis, and many biomarkers are still awaiting careful validation. In veterinary research, EBC collection has been described in conscious animals including calves, pigs, horses, cats and dogs. Numerous studies performed in these domestic animals not only contributed substantially to the current knowledge about the potentials of EBC-based diagnoses but also demonstrated pitfalls in EBC collection, analysis and interpretation. This review summarizes information about the collection of EBC and the interpretation of EBC results, particularly with respect to proteins, leukotrienes, hydrogen peroxide, urea, ammonia and pH. Published data emphasize the need to standardize approaches to produce reproducible EBC data. Quantifying the concentration of the EBC component of interest exhaled in a defined volume of exhaled breath (instead of comparing concentrations of this component analysed in liquid EBC) is an important step of standardization that might help to overcome methodological limitations deriving from the EBC collection process. Although information is based on domestic animal studies, it contributes to the general understanding in EBC research-independent of any particular mammalian species-and opens new perspectives for further studies.

The currently accepted 'gold standard' tuberculosis (TB) detection method for veterinary applications is that of culturing from a tissue sample post mortem. The test is accurate, but growing Mycobacterium bovis is difficult and the process can take up to 12 weeks to return a diagnosis. In this paper we evaluate a much faster screening approach based on serum headspace analysis using selected ion flow tube mass spectrometry (SIFT-MS). SIFT-MS is a rapid, quantitative gas analysis technique, with sample analysis times of as little as a few seconds. Headspace from above serum samples from wild badgers, captured as part of a randomised trial, was analysed. Multivariate classification algorithms were then employed to extract a simple TB diagnosis from the complex multivariate response provided by the SIFT-MS instrument. This is the first time that such multivariate analysis has been applied to SIFT-MS data. An accuracy of TB discrimination of approximately 88% true positive was achieved which shows promise, but the corresponding false positive rate of 38% indicates that there is more work to do before this approach could replace the culture test. Recommendations for future work that could increase the performance are therefore proposed.

Diagnostic tests for some conditions affecting cattle, such as tuberculosis, are often expensive and of long duration, requiring diagnostic tests involving more than one visit by a qualified vet. An alternative rapid and non-invasive diagnostic test would be desirable. One possibility is the use of breath testing, which has been shown to have diagnostic potential in humans. The development of a device for taking a representative breath sample from a bovine animal is described. Six devices using different configurations were assessed over three separate testing days for their ability to take a representative breath sample which does not cause undue stress to the animal and which is easy for an operator to use. The main factors affecting the sample integrity was dead space, however temperature played a role. The best samples causing the lowest stress to animals were taken using a nostril sampler. The nostril samplers were then used to take breath samples from cattle with and without tuberculosis which were then analysed using selected ion flow tube mass spectrometry and gas chromatography-mass spectrometry to demonstrate proof-of-principle.

This study aimed (i) to assess the ability of electronic nose (e-nose) technology to differentiate between blood samples of experimentally infected and non-infected subjects, and (ii) to evaluate e-nose responses given by volatile organic compounds in relation to the acute phase reaction