Anyway, veganism is abstaining from consuming animal products. Bacteria are not animals, therefore antibiotics are not a contradiction.

I’m a vegan and for Me it’s about not exploiting nonhumans. Most nonhumans can’t advocate for themselves, so it’s wrong to use them for labour. As a vegan, I’m fine with eating sponges, which are technically animals but have no neurons. But I’m not fine with exploiting non-animal creatures that have neurons.