As of 2011, treatment options for gram-negative rods include antibacterials such as tigecycline, a glycylcycline, and doripenem, a new carbapenem, states the National Center for Biotechnology Information. The Food and Drug Administration has approved doripenem and tigecycline. Using tigecycline and polymyxins, including colistin, have produced successful outcomes against E. coli.
Gram-negative bacteria include E. coli, Acinetobacter spp., Klebsiella spp and P. aeruginosa, explains the National Center for Biotechnology Information. Infection rates by strains such as P. aeruginosa continue to rise in the United States. Patients who have cystic fibrosis or who depend on ventilators in intensive care units are especially vulnerable to the resistant bacteria. Researchers were not developing antibacterial agents to combat Acinetobacter spp. as of 2011, based on an article published by NCBI.