To protect against C. difficile infection:
What is so frightening about C. difficile is that it is often spurred by antibiotics. The drugs wipe out the targeted illness, like a urinary tract or upper respiratory infection, but they also kill off large portions of the healthy bacteria that normally live in the digestive tract. If a person [who has just taken antibiotics] comes into contact with C. difficile, or already has it, the disruption to the beneficial bacteria creates an opportunity for the harmful bacteria to flourish.
The NY Times article doesn’t mention fermented foods.
Thanks to Ashish Mukharji.