Salmonella, Shigella, and Escherichia coli are three enteric bacteria that manage to infect and cause almost 400,000 cases of gastroenteritis each year in the United States. Antibiotic therapy used to control these microorganisms is becoming ineffective due to antibiotic resistance. Instead of using antibiotics that kill to control infections, a new approach to drug therapy is to target pathogenicity islands which confer virulence genes including antibiotic resistance onto their hosts. Pathogenicity islands are spread through conjugation at high rates and across widely divergent species. However, the signaling mechanisms of conjugation are highly conserved traits that can serve as novel drug targets. By using competitive inhibitors to lower the rate of conjugation, such as those recently studied in both E. coli and Yersinia, the spread of pathogenicity islands can be prevented and infectious diseases can be controlled.