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Chitosan is derived from chitin and is a linear polymer of ?-1,4-linked N-acetyl-D-glucosamine and D-glucosamine. It has been reported to exhibit antimicrobial activity against a variety of microorganisms but is most inhibitory to yeasts and molds. Chitosan has been used to make microparticles that are effective delivery compounds of drugs and vaccines. <P>Our initial studies used chitosan microparticles as a carrier for antibodies to E. coli O157:H7 for use as a possible intervention strategy to reduce carriage of this pathogen by cattle; however, cattle receiving chitosan alone had a greater reduction in shedding of E. coli O157:H7 than those fed the chitosan-antibody microparticles. A crossover study to address the impact of chitosan feeding on E. coli O157:H7 shedding in cattle was conducted. Chitosan had a statistically significant effect on E. coli O157:H7 shedding. <P>The purpose of these studies was to determine the mechanism of the chitosan reduction of E. coli O157:H7 shedding in cattle. demonstrated that soluble preparations of chitosan inhibited growth of E. coli O157:H7 and other Gram-negative bacteria although the degree of susceptibility varied between different species. <P>Additional work is needed to evaluate the optimal level of chitosan in cattle feed to reduce or eliminate E. coli O157:H7 shedding and evaluate the influence of chitosan feeding on animal production.
Non-Technical Summary: Results from these studies demonstrated that soluble preparations of chitosan inhibited growth of E. coli O157:H7 and other Gram-negative bacteria although the degree of susceptibility varied between different species. Additional work is needed to evaluate the optimal level of chitosan in cattle feed to reduce or eliminate E. coli O157:H7 shedding and evaluate the influence of chitosan feeding on animal production. <P> Approach: Cattle inoculated with E. coli O157:H7 were administered chitosan microparticles loaded with antibodies to proteins secreted by E. coli O157:H7. Control animals fed chitosan alone had a significantly greater reduction in E. coli O157:H7 shedding. In a followup study, the effects of chitosan feeding on shedding of E. coli O157:H7 shedding in inoculated cattle was studied using a crossover design. The results from this study found that chitosan feeding had a statistically significant effect on shedding of this human pathogen in cattle. The basis for the reduction in E. coli O157:H7 shedding in cattle has been investigated more recently. Results from these investigations have found that chitosan was antimicrobial and inhibits growth of E.coli O157:H7 and other enterics. There was strain-to-strain variation in susceptibility to chitosan, but ug/ml concentrations effectively inhibited growth. These findings suggest that chitosan likely decreases shedding of E. coli O157:H7 in cattle because of its antimicrobial activity.