One thing you could do is to use the Streaming API filter endpoint with track parameters that match the domain names of ‘news’ organisations, thereby picking up news by finding tweets that have URLs pointing to a known news site. Checkout the API here:
You could send something like this in your post data:
track=bbc.co.uk,cnn.com,nytimes.com
With this you can have up to 400 different terms on the stream. In this way you could also focus on a particular region, or language, by only including news organisations that are from that area or use a certain language.
Cheers,
JB.