Hi Guys,
Running Joomla 2.5.8 with K2 v2.5.7
The last few months I have been getting a lot of item spam, I have been deleting them as I get them but want to know how to stop it completely?

Hi. Are you talking about item comments ? You can enable K2 reCAPTCHA in K2 parameters. Also note that the version of K2 you are using is outdated.

Actual articles are being added to the site.

Disable front-end editing. In addition, if your site does not require registration disable registration also. It looks like you have registration enabled in your site and that the default K2 user group that new users are assigned has the permission to create items.