"SANTIAGO -- Chile's salmon farmers are using record levels of antibiotics to treat a virulent and pervasive bacteria, driving away some U.S. retailers including Costco Wholesale Corp, which is turning to antibiotic-free Norwegian salmon.

The coastal waters of Chile, the world's second-largest producer of salmon, are awash with a bacteria known as SRS, or Piscirickettsiosis. The bacteria causes lesions and haemorrhaging in infected fish, and swells their kidneys and spleens, eventually killing them.

Unable to develop an effective vaccine, Chilean farmers have been forced to increase antibiotic use. In 2014, the industry produced around 895,000 tonnes of fish and used 563,200 kilograms (1.2 million pounds) of antibiotics, according to government and industry data. Antibiotic use had risen 25 percent from 2013."

Anthony Esposito reports for Reuters July 23, 2015. [2]