Repurposing dried blood spot device technology to examine bile acid profiles in human dried fecal spot samples.

Dried blood spot (DBS) analysis has existed for >50 years, but application of this technique to fecal analysis remains limited. To address whether dried fecal spots (DFS) could be used to measure fecal bile acids, we collected feces from five subjects for each of the following cohorts: 1) healthy individuals, 2) individuals with diarrhea, and 3) Clostridioides difficile-infected patients. Homogenized fecal extracts were loaded onto quantitative DBS (qDBS) devices, dried overnight, and shipped to the bioanalytical lab at ambient temperature. For comparison, source fecal extracts were shipped on dry ice and stored frozen. After 4 mo, frozen fecal extracts and ambient DFS samples were processed and subjected to targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based metabolomics with stable isotope-labeled standards. We observed no differences in the bile acid levels measured between the traditional extraction and the qDBS-based DFS methods. This pilot data demonstrates that DFS-based analysis is feasible and warrants further development for fecal compounds and microbiome applications.NEW & NOTEWORTHY Stool analysis in remote settings can be challenging, as the samples must be stored at -80°C and transported on dry ice for downstream processing. Our work indicates that dried fecal spots (DFS) on Capitainer quantitative DBS (qDBS) devices can be stored and shipped at ambient temperature and yields the same bile acid profiles as traditional samples. This approach has broad applications for patient home testing and sample collection in rural communities or resource-limited countries.

Quantification of Fecal Spot Production as a Measure of Environmental Contamination Based on Common Bed Bug (Hemiptera: Cimicidae: Cimex lectularius L.) Population Size.

The presence of fecal spots has often been used to verify the existence of a bed bug (Cimex lectularius) infestation. However, no research has been conducted to determine how much fecal material that a bed bug population produces over time. In this study, the number of fecal spots that each nymphal life stage was capable of producing after a bloodmeal was quantified. Adult fecal spots were also quantified to determine if there was consistent production between feedings. During this study, it was discovered that bed bugs produced visible fecal spots and clear spots that were only visible under ultraviolet light. Therefore, three types of fecal spots were quantified: dark feces, light feces, and clear spots. Clear spots were produced in greater amounts (38.5-55.5%) than either dark spots (27.3-40.7%) or light spots (17.3-21.9%). For example, 5th instar bed bugs were thought to produce an average of 21 spots (dark and light) after a single bloodmeal. However, using the ultraviolet light, it was found that the 5th instars actually produced an average of 44.7 spots. Using the total fecal spot data collected during this study, researchers could project contamination potential for an infestation starting with a single gravid female over 30, 60, and 90 d. In addition, the amount of area covered by these spots was projected to be over 12 m2 in just 3 mo, which could greatly reduce the environmental and aesthetic quality of a home.