Researchers from Tufts University School of Medicine have identified an isolate of E. coli which is resistant to the class of antibiotics carbapenems – used to treat life threatening disease-causing bacteria.
The study, published in Antimicrobial Agents and Chemotherapy, revealed how bacteria are able to eventually become resistant to certain classes of antibiotics.
Infections that become resistant to antibiotics lead to a considerable increased risk of infection, which can cause serious public health concerns.
An enzyme called carbapenemase destroys the antibiotic which is used to treat the infection.
The research, led by Stuart Levy, M.D., Professor of Molecular Biology & Microbiology and of Medicine, aimed to identify why this particular isolate of E. coli is resistant to carbapenem when carbapenemase is absent.
Levy said:
“The Centers for Disease Control and Prevention has documented a significant increase in Carbapenem-resistant Enterobacteriaceae (CRE) – so-called ‘super bugs’ that have been found to fight off even the most potent treatments. We knew that bacteria could resist carbapenems, but we had never before seen E. coli adapt so extensively to defeat an antibiotic. Our research shows just how far bacteria will go with mutations in order to survive.”
They found that the E. coli mutated four different times before becoming resistant to carbapenems. In addition, the bacterium had a mutation of the protein marR which controls how the it reacts in the presence of antibiotics. The scientists also identified a new protein called yedS which is normally inactive in E. coli.
Over the last 10 years, the prevalence of CRE germs has gone up from 1% to 4% in the U.S., according to the Centers for Disease Control and Prevention.
18% of acute hospitals in the U.S. reported a case of at least one CRE infection during the first 6 months 2012.
The isolate of E. coli came from a patient in Peking Union Medical College Hospital. In China antibiotics are often over-prescribed, making drug resistance a very serious public health concern.
Levy added:
“The first quinolone-resistant strains of bacteria came out of China, where we see that the drugs of last resort begin being used, because the other drugs don’t work after so much overuse.”
Earlier this month, geneticist Mohammed Bakkali, from the University of Granada in Spain, demonstrated that using antibiotics can make non-resistant bacteria become more resistant because they acquire the DNA of resistant bacteria. His study was published in the March 13th issue of Archives of Microbiology.
Written by Joseph Nordqvist