Overuse of antimicrobial agents and problems with infection control practices have led to the development of multidrug-resistant gram-negative bacterial infections. We used to use carbapenems as the main option in several countries for those severe infections; however, now there are several mechanisms of resistance, including carbapenemase production among Acinetobacter, Pseudomonas, and Klebsiella isolates. Subsequently, carbapenems are sometimes not active against those serious infections. That is why clinicians around the world have reconsidered the use of older antimicrobial agents, including polymyxins. — Matthew Falagas, MD.
The above quote was taken from an interview by Luke F. Chen, at the Infectious Diseases Society of America 2010 Annual Meeting. A study of MDRGN in long-term care facilities, reported in 2010, concluded that patients with severe dementia who require assistance with the activities of daily life are at high risk of MDRGN co-colonization and may be the "superspreaders" of MDRGN in these facilities.