Sodium chlorate kills Salmonella, E. coli in livestock.

When fed in low doses, sodium chlorate kills S. typhimurium and E. coli O157:H7 in pigs and cows. USDA-ARS scientists (Food and Feed Safety Research Unit, Southern Plains Agricultural Research Center, 2881 F&B Rd., College Station, TX 77845) have shown that levels of these bacteria can be reduced in the intestinal tract of pigs and cows if they're given sodium chlorate before they are slaughtered.

Because the gut and lymph tissue of meat animals and chickens are major reservoirs for Salmonella and E. coli O157:H7, this research offers a practical approach for reducing concentrations of these pathogens. Fewer bacterial pathogens in the gut can significantly reduce the chance of carcass contamination during processing.

These two bacteria can live both aerobically and anaerobically. That makes them different from most gut bacteria, which are anaerobes. Salmonella and E. coli O157:H7 contain the enzyme nitrate reductase. This enzyme coincidentally converts chlorate to chlorite, which kills the harmful bacteria. Beneficial bacteria in the intestinal tract lack nitrate reductase, so they are not affected by chlorate. The cost of using sodium chlorate at a meat processing facility could be less than 10 cents per pig, according to estimates by ARS microbiologists.

In laboratory studies, 45 weaned pigs were fed up to 0.04 gram of sodium chlorate per kilogram of body weight after they were infected with S. typhimurium. Within 16 hours, the treatment produced a 150-fold reduction in the number of pathogenic cells in the intestines.

Before this approach could be widely used in the United States, the FDA would need to approve its use. But if results from large field trials hold up, a system may evolve that involves feeding chlorate to animals before they're transported to slaughter. Another approach would be to add chlorate to drinking water at the slaughterhouse.

There are about 1.4 million cases of salmonellosis and 73,000 cases of diarrheal illness caused by E. coli O157:H7 in the United States each year. ARS researchers have applied for a patent covering their approach.

Further information. Robin Anderson; phone: [phone]; fax: [phone]; email: [e-mail].