scrap twitter feeds for user id based on certain keywords

I require a script that can be run constantly to monitor twitter feeds for certain keywords. The script should extract the twitter id of the poster and log it into a text file or a database (developer can decide) developer is encouraged to do research on the internet and tweak/modify any existing scripts available that performs this action. Developer is encouraged to review Scrapy and see if it is fit for this purpose <[login to view URL]>