2000 years old tetracyclin beer?

When tetracyclin was detected in large quantities in the bones of ancient Sudanese Nubians from 350-550 CE, many wondered if it was accidental. But evidence suggests that it was manufactured on purpose by growing streptomyces in beer. It seems to have been used therapeutically, including in children:

"“The bones of these ancient people were saturated with tetracycline, showing that they had been taking it for a long time,” he says. “I’m convinced that they had the science of fermentation under control and were purposely producing the drug.”

Even the tibia and skull belonging to a 4-year-old were full of tetracycline, suggesting that they were giving high doses to the child to try and cure him of illness, Nelson says."