New treatment options against antibiotic-resistant bacteria discovered

Researchers are developing a new method for identifying effective antimicrobials
In recent years, hospitals have experienced a dramatic increase in the number of cases of highly contagious and difficult to treat antibiotic-resistant bacteria. These include so-called carbapenem-resistant Enterobacteriaceae (CRE). Diseases with these resistant bacteria often have fatal consequences for those affected. Researchers have now developed a promising method for the identification of new antimicrobial agents that target these organisms.

Antibiotic-resistant bacterial strains are a major threat to human health. If treatment with antibiotics is not possible, many diseases can have fatal consequences. Scientists from Harvard Medical School and the Beth Israel Deaconess Medical Center have now teamed up to develop a promising methodology that will allow physicians to identify new antimicrobial agents that target these types of organisms. The physicians published the results of their study in the journal "ASSAY and Drug Development Technologies".

Scientists from Harvard Medical School and the Beth Israel Deaconess Medical Center have now tried to find out which medicines can be used to fight antibiotic-resistant bacteria. These dangerous strains of bacteria are on the rise worldwide. (Image: jarun011 / fotolia.com)

What exactly are CRE bacteria??
So-called CREs are Gram-negative bacteria that often affect a gene responsible for the processing of carbapenem and other antibiotics. These enzymes are located on mobile genetic elements that can jump from one bacterium to another and are also called plasmids, say the experts. The two most common types of CRE bacteria are the carbapenem-resistant Klebsiella species and the so-called carbapenem-resistant Escherichia coli. Patients infected with these bacteria have few options for effective antibiotic treatment, physicians at Harvard Medical School add in a press release.

Development of new antibiotics is declining
Carbapenem-resistant organisms have recently been classified by the United States Centers for Disease Control and Prevention (CDC) in the highest threat category, said Professor James Kirby of the Beth Israel Deaconess Medical Center. Unfortunately, there are often no effective or toxic antimicrobial options to treat CRE. These bacteria are particularly dangerous because their abundance is increasing throughout the world, adds the professor. Although there is an urgent need for new antimicrobial agents against CRE and other antibiotic-resistant bacteria, the number of new antibiotics that have been developed and subsequently approved in recent decades has been steadily declining, the researchers warn.

Azidothymidine, spectinomycin and apramycin are effective against large numbers of CRE strains
To identify new or existing drugs that are effective against multidrug-resistant CRE bacteria, the experts studied about 10,000 compounds with known activity of so-called bioactive molecules. These include most of the previously approved drugs, say the doctors. Through a high-throughput screening process, scientists were able to determine whether certain compounds either directly inhibit the growth of CRE or restore the efficacy of carbapenem against these organisms. In the experiment, 79 compounds were found to inhibit CRE. For example, azidothymidine, spectinomycin and apramycin were effective against a large number of CRE strains, the experts explain.

Two drugs with minimal side effects have great potential
These antimicrobials currently have other uses and have not been considered as an option to treat CRE, the authors say. However, the new findings suggest that they could potentially be used to treat CRE in the future, according to Kenneth Smith of Harvard Medical School. Apramycin and spectinomycin are of particular interest because they have minimal side effects, so they may provide ideal new treatment options for CRE infections, the expert adds. In his opinion, these drugs can not only be used against CRE but also serve as a starting point for further drug development. In particular, these antibiotics could be structurally modified to increase their activity and prevent the occurrence of resistance, the expert explains. (As)