The general rule is that if you keep credit cards purchases under 2,000 dollars you can secure your purchases. However if you spend over 2,000 dollars on credit cards while filing bankruptcy, your purchases may qualify to be revoked.
What happens really depends on the aggressiveness of the credit card company. If they are used before actually filing for bankruptcy you should be okay, however, if they are used after the filing date, the company may be more likely to contest that account in court at the bankruptcy proceeding.
Credit cards (and any other type credit being used) will be included in your bankruptcy. In some bankruptcies, debts are slowly repaid; however, credit card balances generally are not repaid. After bankruptcies are discharged (all debts are absolved), monies once owed to the credit card company is no longer owed.
Your debts will be forgiven as long as the charges didn't happen within a certain period before your bankruptcy papers are filed with the court. There is a time limit in which charges will not be forgiven and you will be expected to pay. They suggest you just cut the cards up when filing.
It is best to refrain from using your credit cards within 6 months prior to filing bankruptcy. If you use them within the 6 months prior to filing, the magistrate may determine that the debt is "too new" to be filed on. I personally filed bankruptcy and was told this by my attorney.
Be careful about using your credit cards excessively just prior to filing bankruptcy, as this may be viewed as fraud and those purchases might be disqualified from your bankruptcy.