Activity and specificity of a mouse monoclonal antibody to ferric aerobactin

We isolated a monoclonal antibody directed against the ferric complex of aerobactin purified from Escherichia coli KH576. This antibody, which we designated MAb AERO1, was identified as an immunoglobulin G, subtype 2. A competitive enzyme-linked immunosorbent assay with MAb AERO1 had a limit of 10 nM for the detection of purified ferric aerobactin and allowed detection of the crude aerobactin produced by various members of the family Enterobacteriaceae isolated from cancer patients with bacteremia. The only two other structurally related siderophores recognized by MAb AERO1 were ferric arthrobactin and ferrioxamine B. These results suggest that the epitope recognized by MAb AERO1 was the lysyl moiety of ferric aerobactin. We also showed that MAb AERO1 reduced the growth of an aerobactin-producing strain of E. coli in newborn calf serum, which indicates that it might be effective in reducing the severity of infections caused by bacteria for which the production of aerobactin is an important virulence factor.