This here is a stain of bacterium helicobacter pylori, which was found in the 1980s to the cause of stomach ulcers - previously thought to be caused from spicy food or stress. 

This was determined by two Australian scientists Marshall and Warren who earned a Nobel Prize for their work in 2005. The main problem with studying bacteria that lives in the stomach is that it’s very hard to culture- many other scientists had tried before Marshall and Warren but all failed in growing the bacteria.
Marshall and Warren succeeded in culturing H. Pylori by accidentally leaving out their cultures for 5 days over the Easter holidays.

Suggesting that bacteria was the cause of ulcers was pretty far out at the time, so Marshall ingested a beaker full of  H.pylori  to prove their work. He became very nauseous and was vomiting. An endoscope some days later showed  H.pylori to be the offender,  and antibiotics improved his condition. Within a couple of years, antibiotics were being prescribed internationally for stomach ulcers.