prnPR Newswire has imposed stricter guidelines to root out "low quality content" and crack down on releases more focused on gaming search engines than providing analysis and useful information.

Google sent tremors through press release services with its Panda 4.0 update late last month. A study by Seer Interactive on May 29 said Google dropped the search rankings on millions of individual press releases online, particularly those published by Vocus'

PR Newswire senior VP Jason Edelboim said the recent update to Google's algorithm amounts to a "technology-based editorial guidelines for content quality." He said PRN editorial staff will review releases for analysis and original content, use of varied formats rather than template copy, length to cut down on short releases intended only as link-bait, and overuse of keywords.

Sarah Skerik, VP of strategic communications for PRN, said in a blog post today that an audit of PRN's site after the Google update identified spam press releases garnering substantial traffic because of "black hat" SEO tactics. She said most of PRN's customers will not be affected by the beefed up content guidelines and stressed that, in addition to the millions of visitors to its website, the company's proprietary distribution network reaches a large global audience.

Google's update, known as Panda 4.0, also whacked sites like eBay and