UPDATE 1-Cepheid gets FDA nod for bacterial infection test

* Says FDA OKs test for C. difficile infection

* Shares up 8 pct in pre-market trade

July 13 (Reuters) - Cepheid Inc (CPHD.O) said the U.S. health regulator granted marketing approval for the company's diagnostic test to detect a possibly fatal bacterial infection, sending its shares up 8 percent.

The company, which makes systems and tests for genetic analysis, said the Xpert test to detect infection of bacterium Clostridium difficile in the gut will be available for shipment in the week of July 20.

Clostridium difficile infection can result in anything from severe diarrhea to death.

Shares of the Sunnyvale, California-based company were up 8 percent at $9.15 in pre-market trade. They closed at $8.47 Friday on Nasdaq. (Reporting by Vidya L Nathan in Bangalore; Editing by Anil D'Silva)