Aerobactin production linked to transferable antibiotic resistance inEscherichia colistrains isolated from sewage

The production of aerobactin has been suggested to be a virulence factor in Escherichia coli. We have studied the production of aerobactin in 155 E. coli strains, isolated from sewage, which carry conjugative antibiotic resistance plasmids, and 88 (57%) of these strains produced aerobactin, and 59 (38%) co-transferred production of the siderophore and antibiotic resistance. In 35 (22%) of the transconjugants, both characters seemed to be encoded into the same plasmid. Those aerobactin-producing-antibiotic resistance plasmids had different sizes and antibiotic resistance patterns. The ecological implications of these results are discussed.