Opening the fridge and finding the cheese you bought covered in a furry blue or green mould is a decidedly unpleasant experience. Whether or not it is still OK to eat the mouldy cheese depends on the type of cheese.
Moulds that are not part of the cheese-making process itself can act as host to a bevy of dangerous bacteria, including listeria and salmonella.
Certain cheese types, such as Stilton and blue cheeses generally, are mouldy to begin with. However, if you notice mould that appears different from the cheese's natural mould, follow the same advice for non-mouldy cheese. Throw it in the bin.
If you encounter mould on a hard cheese such as parmesan or a semi-hard cheese such as cheddar, it might be possible to save the rest of the cheese. Remove the mouldy portion on a hard or semi-hard cheese by cutting at least 2.5 cm (1 inch) around the mould. Make sure the knife doesn't touch the mould so that you don't risk contaminating the rest of the cheese.
Food safety organisations recommend that you discard soft cheeses, such as cream cheese and cottage cheese, that have mould on them.
Shredded or grated cheese that has grown mould should also be chucked out. Even if you attempt to remove all the mouldy pieces of cheese, there is the risk that some mould spores will remain.