Staphylococcus aureus may develop lasting resistance to vancomycin, as indicated by a study published on August 28, 2024, in the open-access journal PLOS Pathogens by researchers Samuel Blechman and Erik Wright from the University of Pittsburgh, USA.
Despite years of extensive use of the antibiotic vancomycin, instances of S. aureus developing resistance are exceedingly rare, with only 16 cases reported in the U.S. to date. Mutations that make bacteria resistant to vancomycin allow them to survive in its presence, but this often comes with a drawback. Strains of vancomycin-resistant S. aureus (VRSA) tend to grow more slowly and may lose their resistance traits when vancomycin is not available. However, the factors contributing to vancomycin’s continued effectiveness and the potential adaptations of VRSA strains have not been thoroughly examined.
In their research, the scientists cultivated four VRSA strains both with and without vancomycin to observe their evolution. They discovered that strains nurtured in a vancomycin-rich environment developed further mutations in the ddl gene, which has been linked to a dependence on vancomycin. These alterations enabled these VRSA strains to grow more rapidly in the presence of the antibiotic. Unlike the original strains, which tended to quickly lose their resistance when vancomycin was absent, the modified strains sustained their resistance across several generations, even without the antibiotic present.
This research indicates that the current stability of vancomycin’s efficacy should not be assumed. The usual trade-off associated with vancomycin resistance can be mitigated if bacteria are allowed to proliferate while exposed to the antibiotic. With antibiotic resistance escalating as a significant public health concern, studies like this one highlight the urgent need to create new antibiotics.
The authors conclude: “The antibiotic vancomycin has kept the superbug MRSA at bay for many years. This new study illustrates that we may not be able to rely on vancomycin indefinitely.”
