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 infections and diseases using anti-flagellin antibodies in humans, other animals and birds.