Introduction
The ability of bacteria to proliferate within a particular environmental niche in the host is essential for initiation of an infection. Iron is an essential nutrient for the growth of coliform bacteria in the bovine mammary gland. However, the bovine mammary gland is an iron-restricted environment. Iron is primarily bound to citrate in milk to form ferric dicitrate. Coliform bacteria have developed the ability to acquire iron directly from naturally occurring organic iron-binding acids such as citrate. The bacterial citrate-mediated iron uptake system has a novel transcription initiation mechanism starting with the coupling of ferric citrate and the cell surface receptor, FecA.
The FecA expressed by coliform bacteria isolated from bovine mastitis was antigenically conserved among strains of E. coli and Klebsiella spp. The objective of this study was to investigate the effects of immunizing cows with FecA on experimentally-induced coliform mastitis.