No idea what the hell happened with that breakfast, hmmm. You would have mentioned odd stuff.
I knew a lot of bacteriology a semi century ago, but not now, for sure.
I seem to have improved my gut bacteria with my yogurt (pro biotic) fruit smoothies, but that could easily just be magical thinking. Memories - a smart swedish friend never went to Mexico without having charcoal tablets handy, just in case. Don't trust me or her on that, just mentioning it.
My own worst episode, oh gawd, was in Mexico on a romantic vacation, where I developed the (to me then) unique ability to have diarrhoea in the toilet and heave voluminous discharge by throwing up at the same time in the shower, luckily close by.
(I did throw up again, in Customs....) It went away once I had lunch back in LA. Scrambled eggs and toast.
I blamed that one on a certain cafe, called The Deer.
A friend's later husband got shigellosis in Mexico, more dire stuff with that; she, a nurse, got him to a hospital.
Oh, I tend to like bubbly mineral water, as an "instead of" drink, both because I don't mind it, and for the minerals (Gerolsteiner or Pellegrino).
edit, glad you have that friend, up to date on all this stuff.
Adds, sometimes it's not a pathogen (or so I learned back then) but a severe difference in bacterial flora. And sometimes it may be.