Effect of sodium chlorate on Salmonella typhimurium concentrations in the weaned pig gut

Salmonella cause economic losses to the swine industry due to disease and c ompromised food safety. Since the gut is a major reservoir for Salmonella, strategies are sought to reduce their concentration in pigs immediately bef ore processing. Respiratory nitrate reductase activity possessed by Salmone lla also catalyzes the intracellular reduction of chlorate (an analog of ni trate) to chlorite, which is lethal to the microbe. Since most gastrointest inal anaerobes lack respiratory nitrate reductase, we conducted a study to determine if chlorate may selectively kill Salmonella within the pig gut. W eaned pigs orally infected with 8 x 10(7) CFU of a novobiocin- and nalidixi c acid-resistant strain of Salmonella Typhimurium were treated 8 and 16 h l ater via oral gavage (10 ml) with 0 or 100 mM sodium chlorate. Pigs were eu thanized at 8-h intervals after receiving the last treatment. Samples colle cted by necropsy were cultured qualitatively and quantitatively for Salmone lla and for most probable numbers of total culturable anaerobes. A signific ant (P < 0.05) chlorate treatment effect was observed on cecal concentratio ns of Salmonella, with the largest reductions occurring 16 h after receivin g the last chlorate treatment. An observed treatment by time after treatmen t interaction suggests the chlorate effect was concentration dependent. Chl orate treatment may provide a means to reduce foodborne pathogens immediate ly before harvest.