University at Buffalo (N.Y.) researchers found three antibiotics used together can destroy the deadly strain of E. coli carrying mcr-1 and ndm-5.
Typically, presence of the mcr-1 and ndm-5 genes makes the E. coli bacterium immune to last-resort antibiotics. However, the combination of aztreonam, amikacin and polymyxin B can kill the strain within 24 hours. The combination also prevented any regrowth.
Researchers examined dozens of combinations of more than 15 antibiotics paired with polymyxin B. A combination of polymyxin B and either aztreonam or amikacin eliminated the E. coli strain, but researchers saw regrowth to initial levels after 96 hours. Only the combination of all three antibiotics both eliminated the strain and stopped it from growing again.
"The threat of gram-negative bacteria, including E. coli carrying mcr-1, is worrisome," says Zackery Bulman, PharmD, study author and a former postdoctoral fellow at the UB School of Pharmacy and Pharmaceutical Sciences, who is now an assistant professor at the University of Illinois at Chicago College of Pharmacy. "We believe that the appearance of mcr-1 and ndm-5 in patients may be a harbinger for what is to come. The golden era of antibiotics isn’t over yet, but we wanted to help clinicians prepare therapeutically for the occurrence of these strains."
The researchers published their findings in mBio, a journal for the American Society of Microbiology.