With the rise of carbapenem-resistant bacteria, colistin has increasingly become an antibiotic considered the last line of defense for hard-to-treat infections. According to the Centers for Disease Control and Prevention
, at least 2 million people in the United States become infected with antibiotic-resistant bacteria and 23,000 die as a result each year. Bacteria can form antibiotic resistance–and dangerous infections can occur in people–through exposure to antimicrobial agents. The drugs used to fight the bacteria may destroy certain germs, but some microbes are naturally stronger and more resilient and can resist the effects of the drugs. Once the antibiotics kill off much of the pathogenic bacteria, as well as the beneficial microflora present in our bodies, those drug-resistant bacteria unharmed by the treatment can then grow and take over. That resistance can then spread to other bacteria.
“The surprise wasn’t that we found it in a human; the surprise was that we found it in association with a second resistance gene, which was the carbapenem-resistance gene. That’s the new finding.” - Barry Kreiswirth, PhD
In this case detailed in the new study, while the mcr-1
- and blaNDM-
5-harboring E. coli
was resistant to both carbapenem and colistin, the isolate did show susceptibility to the antibiotics aztreonam, amikacin, gentamicin, nitrofurantoin, tigecycline, and trimethoprim-sulfamethoxazole.
gene that we found in our strain has also been found in other strains throughout the United States,” said Dr. Kreiswirth
during the interview with Contagion
, explaining that isolates containing mcr-1
have been found in pig and bovine samples. He noted that it wasn’t unforeseen to find the colistin-resistance gene in animal reservoirs as the antibiotic has been used in cattle and pig feedlots. “The surprise wasn’t that we found it in a human; the surprise was that we found it in association with a second resistance gene, which was the carbapenem-resistance gene. That’s the new finding.”
As Dr. Kreiswirth and his team continue to study mcr-1
in the United States, he pointed out a recent study
on the finding of a second colistin-resistance gene dubbed mcr-2
, and the possibility that other still-unidentified resistance genes are out there.
More of the interview with Dr. Kreiswirth is available here:
What's Surprising About the Discovery of MCR1_NJ?
Developing New Antibiotics Can Control 'Superbug' Outbreaks
What Makes a 'True' Superbug?
How Can We Fight the Spread of Antibiotic Resistance?
Challenges of Obtaining FDA Approval for Novel Agents
Who is Most Vulnerable to Antibiotic-Resistant Organisms?
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