That is likely the intent. It seems likely that you would have different doses for different diseases, probably with some overlap (akin to Gram-staining, for example).

The author was focused on consumer applications:

> "And instead of producing green fluorescent proteins, the sensor bacteria, easily ingested by just eating a pro-biotic yogurt, could produce an enzyme that makes a colored pigment that would dye someone’s stool, making the color change easy to spot after a bowel movement."The development of such bacteria would also help reduce the need for repeated doctor visits or expensive procedures like colonoscopies. If only every medical test was as simple as eating what you probably already eat for breakfast."

I disagree with that interpretation based on the text you have selected. It does not reference a consumer market (which would be a nightmare scenario if this popped up in health food stores), and explicitly uses the term "medical test". If you have a colorectal or digestive problem, you are already bringing stool samples from home to the lab, and dosing on a diagnostic substance prior is common enough before different examinations (for example, radioactive iodine). I think that this approach is just combining the two with a novel bacterial agent.

I once ate too much red velvet cake, and had the experience of pooping a bright red. Yes, it was a bit shocking, but funny once I knew what happened. If I were expecting it, I'd have been able to delight in the weirdness.

I got the chance to do this later on, however: I took a medicine for a urine tract infection which made my urine look nearly neon yellow. I knew it was possible, and it wasn't a big deal. Expecting the color change makes a difference.