Gastrointestinal tract detection methods, devices and systems

A gastrointestinal tract ingestible device, comprising:

• a gastrointestinal tract ingestible housing comprising a chamber;
• a composition in the chamber, the composition comprising:
• a dye capable of binding to or reacting with a target component of a viable prokaryotic cell from a sample collected from the gastrointestinal tract from an exterior of the housing, wherein the dye exhibits fluorescence that is measurably altered when the dye is bound to or reacted with the target component of the viable prokaryotic cell;
• and
• a reagent capable of selectively lysing eukaryotic cells;
• and
• a system including a light source and a light detector in the housing,
• wherein:
• the system is configured to detect fluorescence from the reaction of the dye from the chamber and the target component of the viable prokaryotic cell from the sample collected from the gastrointestinal tract from the exterior of the housing.