(Xinhua) A new approach to fight bacterial infections, developed at the Massachusetts Institute of Technology (MIT) and the Boston University (BU), could help prevent bacteria from developing antibiotic resistance and kill those that have already become resistant.

Researchers from both schools have engineered a virus that knocks out bacterial defense systems, enhances the effectiveness of antibiotics. The work is reported Monday in the online issue of the Proceedings of the National Academy of Sciences (PNAS).

Antibiotic-resistant bacteria poses a serious and growing health risk. The U.S. Centers for Disease Control and Prevention estimated that the antibiotic-resistant bacterium MRSA, or methicillin-resistant Staphylococcus aureus, causes about 94,000 infections and contributes to 19,000 deaths annually in the United States.

New drugs are needed to combat these super bugs, but very few new antibiotics have been developed in the past few decades. ‘There are a lot of targets to go after, but people haven’t been able to find the drugs,’ said Timothy Lu, lead author of the paper and an MD candidate in the Harvard-MIT Division of Health Sciences and Technology.

Lu and James Collins, Howard Hughes Medical Institute investigator and professor of biomedical engineering at BU, took anew approach: engineering existing bacteriophages (viruses that infect bacteria) to attack specific targets. ‘It’s much easier to modify phages than to invent a new drug,’ said Lu.

The engineered viruses described in the PNAS paper attack the SOS system, a bacterial DNA repair system enlisted when bacteria are exposed to antibiotics that damage DNA, and other gene networks. Used in conjunction with traditional antibiotics, the viruses undermine bacterial defense systems and prevent resistance from developing.

The researchers tested their phages with three major classes of antibiotics (quinolones, beta-lactams and aminoglyclosides) and had good results with all three. In mice infected with bacteria, those treated with both engineered bacteriophage and antibiotics had an 80 percent survival rate, compared with 50 percent for mice treated with natural bacteriophages and antibiotics, 20 percent for mice treated only with antibiotics, and 10 percent for untreated mice.

‘This work lays the groundwork for the development of a library of bacteriophages, each designed to attack different bacterial targets,’ said Lu.

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