Last week, a Subway customer found a mouse in his sandwich . We all have to deal with the fact that we live in a world where that happened. But that doesn't mean the chain isn't interested in improving its food — in fact, it just announced some big changes.This summer, Subway said it would start to transition away from chicken that was raised with human antibiotics. But now, the chain has set its sights even higher : Starting in March of 2016, Subway will start serving chicken raised without any antibiotics. Later next year, it will also introduce turkey raised without antibiotics and expects to serve only this type of turkey within three years. It'll be quite a while until all Subway meat is antibiotic-free, though: The company expects pork and beef to make the transition by 2025.The recent no-antibiotics announcement comes just a month after Subway received an ugly "F" rating from the NRDC for its use of meat raised with antibiotics. But with this new pledge, the company seems to be joining the ranks of Panera, Chipotle, and McDonalds in phasing those products out.By the way, we're not talking about depriving animals of medicine they need if they get sick. Farms often dose livestock with a small amount of antibiotics at all times to stave off potential infections and help the animals grow bigger. But that constant antibiotic use has been tied to the increasingly stubborn problem of antibiotic resistance — and those scary superbugs can be transmitted to humans. So we're happy to see another restaurant hopping on the antibiotic-free train.As for the rodent stowaway? We have no comment.