...depends what you mean anywhere.... if anywhere means everywhere then I would say NO. I am sure there are lots of places that except the Am. Express credit card however if you plan going to an average Czech pub (I am not talking about a fancy restaurant), you better have some cash on you. Usually, you can see stickers on the restaurant/ store door that will give you an idea what cards are accepted there.
VISA and/or MASTERCARD are preferable to AMEX at any rate. Forgive me my saying so, but the question whether you can use AMEX anywhere is either out of ignorance or arrogance. NB If every single place in the US accepts AMEX, then I am a monkey`s uncle.
