Colistin is the last agent used to combat bacteria that are resistant to the strongest antibiotics. Colistin has remained the best tool available to treat multidrug resistant bacteria because bacteria were not exchanging genes for its resistance. This latest discovery shows that colistin may be losing its effectiveness in antimicrobial therapy. Now, bacteria may be exchanging resistance genes for colistin.Alarms sounded in the microbiology community in late 2015 when the first transferrable gene for colistin-resistance was identified in China. Since the report, the global health community has monitored and searched for the occurrence of this gene in the food supply and in humans. This colistin-resistance gene has been reported in Europe and Canada and, as of now, is reported in the U.S.
A clinical sample from a urinary tract infection was collected from a patient in a military treatment facility in Pennsylvania. The sample was sent to the Walter Reed National Military Medical Center (WRNMMC) where colistin susceptibility was tested. The results showed that no safe dosage of colistin would be effective to treat such a bacterial infection.
“Colistin is one of the last efficacious antibiotics for the treatment of highly resistant bacteria. The emergence of a transferable gene that confers resistance to this vital antibiotic is extremely disturbing. The discovery of this gene in the U.S. is equally concerning, and continued surveillance to identify reservoirs of this gene within the military healthcare community and beyond is critical to prevent its spread,” reported Dr. Patrick McGann, MRSN, WRAIR