The present invention provides a novel class of monoclonal antibodies which have a high affinity, broad spectrum neutralizing reactivity to flagellin from various Gram-negative bacteria including, but not limited to, E. coli, Salmonella, Serratia, Proteus, Enterobacter, Citrobacter, Campylobacter and Pseudomonas. The present invention further provides methods of treating inflammatory bowel disease (IBD) and methods of treating enterobacterial infections using anti-flagellin antibodies in humans, other animals and birds.