It's possible it still had some antibiotic properties, lots of commonly used drugs interact with our gut bacteria in varying ways. And indeed a quick search sug

It's possible it still had some antibiotic properties, lots of commonly used drugs interact with our gut bacteria in varying ways. And indeed a quick search suggests that this might be the case: https://pmc.ncbi.nlm.nih.gov/articles/PMC5514548/ https://pmc.ncbi.nlm.nih.gov/articles/PMC5514548/