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Evaluation of Gallium Maltolate on Fecal Shedding of Salmonella in Cattle

Nisbet, David; Nerren , Jessica; Krueger, Nathan; Genovese, Kenneth; Farrow, Russell; Edrington, Thomas; Callaway, Todd; Anderson, Robin; Bernstein, Lawrence
USDA - Agricultural Research Service
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Foodborne illness is a major cause of morbidity and mortality in the United States. Salmonella enterica is the second leading cause of foodborne illness, and causes an estimated 1.4 million cases of gastroenteritis every year. The economic impact of salmonellosis is substantial, with an estimated annual cost of over $3.5 billion due to loss of work, medical care, and life. Salmonellosis is frequently attributed to the consumption of contaminated food products, such as poultry, beef, pork, and eggs. Cattle are a frequent reservoir for Salmonella, and novel strategies aimed at minimizing shedding of Salmonella are important for reducing the incidence of foodborne illness.

Iron withholding is an essential antimicrobial component of the innate immune system. Iron-binding proteins (particularly transferrin and lactoferrin) bind virtually all free iron in mammalian cells and tissues, thereby rendering iron unavailable to most microorganisms. Some pathogenic bacteria, however, can acquire iron directly from these iron-binding proteins. A variety of preventative and therapeutic strategies for bacterial infections have been developed that act by interfering with microbial iron acquisition and utilization. Gallium is a semi-metal that accumulates in inflamed tissue, macrophages, neutrophils, and in some bacteria. The antimicrobial effects of gallium are related to its ability to be a non-functional iron mimic. Bacteria acquire gallium, instead of iron, and incorporate it into metabolic pathways and enzymes that require iron. Many of these enzymes are critical for survival of the bacteria. The net result is inhibition of bacterial replication, and ultimately bacterial death. Recent publications have shown gallium to exhibit bactericidal activity in vitro and in vivo against numerous pathogenic bacteria. Preliminary research conducted in our laboratory demonstrated that gallium maltolate, a complex of gallium and maltol with high bioavailability, significantly inhibits growth of Salmonella enterica serovar Newport in pure culture and in mixed ruminal fluid cultures.

The objective of the current project was to determine whether oral administration of gallium maltolate (GaM) would significantly reduce the numbers of Salmonella shed in the feces of cattle.

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Findings: We found no significant differences between control animals and treated animals in quantitative levels of Salmonella in the feces or in the luminal contents. Likewise, we observed no pattern between control and treated animals in the frequency of positive or negative values in enriched feces, luminal contents, or tissue samples. Data from this study suggests that GaM was not effective at reducing fecal shedding of Salmonella.
Funding Source
Nat'l. Cattlemen's Beef Assoc.
Project number
Bacterial Pathogens
Natural Toxins
Meat, Poultry, Game