The Agriculture Department says three California poultry processing facilities linked to a salmonella outbreak in raw chicken can stay open, for now.

In a statement Thursday, the USDA said Foster Farms, which owns the facilities in Fresno and Livingston, Calif., has made "immediate substantive changes to their slaughter and processing to allow for continued operations."

The department threatened earlier this week to shut down the plants if Foster Farms did not prove that it had made enough changes. Sampling by the USDA in September showed that raw chicken processed by those facilities included strains of salmonella that were linked to the outbreak that has sickened 278 people in 17 states.

USDA said government inspectors will monitor the company's improvements and "continue intensified sampling" of Foster Farms meat for the next three months.

In a Monday letter to Foster Farms, USDA said the positive samples coupled with the illnesses suggest that the sanitary conditions at the facility "could pose a serious ongoing threat to public health." The company had until Thursday to respond.

The outbreak, which has been going on since March, has had a high rate of hospitalizations. The Centers for Disease Control and Prevention said 42 percent of victims were hospitalized, about double the normal rate, and it is resistant to many antibiotics, making it more dangerous.

In a statement Thursday, Foster Farms President Ron Foster said the company has been working for two months to add increased food safety controls.

"This officially validates our progress, but we are not stopping here," Foster said of the company's agreement with the USDA to keep the plants open.

The CDC says the outbreak is ongoing and some illnesses began as recently as two weeks ago. The majority of illnesses have been in California but people in 17 states have been infected, from Texas to Michigan to North Carolina.

Salmonella can contaminate meat during slaughter and processing and is especially common in raw chicken. The infections can be avoided by proper handling and cooking of raw poultry.

The pathogen causes diarrhea, abdominal cramps and fever within a few days of eating a contaminated product and can be life-threatening to those with weakened immune systems.

___

Follow Mary Clare Jalonick on Twitter: http://twitter.com/mcjalonick