Methicillin-resistant Staphylococcus aureus (MRSA) has become a serious problem, forcing doctors to turn to antibiotics other than penicillin or penicillin derivatives, or to different drug cocktails, which are often less effective in treating hospital and community-based infections.
But new Medical Research Council (MRC) funded research from scientists at the University of Cambridge and the Wellcome Sanger Institute has found that some MRSA infections could be tackled—and by using existing antibiotics.
The researchers found that MRSA isolates become susceptible to penicillin in combination with clavulanic acid: A widely used beta-lactamase inhibitor for the treatment of kidney infections during pregnancy.
Using genome sequencing technology, the researchers were then able to identify which genes make MRSA susceptible to this combination of drugs by identifying several mutations centerd around a protein known as a penicillin-binding protein 2a or PBP2a; a protein which enables MRSA strains to keep growing despite the presence of penicillin and other antibiotics derived from penicillin.
The team found that two of these mutations reduced the amount of PBP2a produced, while two other mutations increased the ability of penicillin to bind to PBP2a in the presence of clavulanic acid.
The team then looked at whole genome sequences of a diverse collection of MRSA strains and found that a significant number of them—including the dominant US300 clone in the United States—contained both mutations, suggesting that they too would be sensitive to the combination of drugs.
MRSA infections in two model systems, moths and mice, have since been successfully treated using a combination of the two drugs with the team now looking to expand into human trials.
