A new class of antibiotics can kill methicillin-resistant Staphylococcus aureus (MRSA) bacteria in a preclinical mouse model, a Nature paper reports. With antimicrobial resistance an increasingly serious threat to global public health, it is hoped that the study will aid the development of new, effective, clinically useful antibiotic drugs.

MRSA is a potentially lethal bacterium that is difficult to treat, not only because many strains are now resistant to conventional antibiotics, but also because it forms subpopulations of metabolically inactive, antibiotic-tolerant ‘persister’ cells. Eleftherios Mylonakis and colleagues identified two synthetic retinoid compounds that kill both growing and persister MRSA cells in a lab-based assay. One of these compounds was also effective in treating a mouse model of chronic MRSA infection.

The compounds, which are analogues of vitamin A, have low levels of toxicity and work by disrupting bacterial membranes. Both work synergistically with the common antibiotic gentamicin, and the authors think it is unlikely that bacteria will develop resistance to them. Currently, over 4,000 natural and synthetic retinoids have been described, so it is possible that more antimicrobial candidates will be found amongst them. In the meantime, further development of these two compounds is needed in order to improve their safety profile, and move them closer to clinical trials.