Highly read on rsbl.royalsocietypublishing.org in January

As antibiotic resistance in microorganisms has risen, some scientists have suggested that short, synthetic amino-acid chains, or peptides, that kiWll invading pathogens could make a new therapeutic weapon. But Michelle Habets and Michael Brockhurst at the University of Liverpool, UK, highlight serious potential risks of this strategy.

The researchers exposed the pathogen Staphylococcus aureus — which causes a range of dangerous infections and has developed resistance to many antibiotics — to increasing levels of a synthetic peptide called pexiganan, a candidate treatment for diabetic leg-ulcer infection. Over several tens of generations, the bacteria evolved resistance to the peptide. Furthermore, some bacteria also evolved resistance to HNP-1, a natural human peptide that is an important part of innate immunity, which represents the immune system's first line of defence.

The authors say that such cross-resistance could undermine the innate immune system's ability to prevent superficial infections from progressing to life-threatening disease.

Biol. Lett. http://dx.doi.org/10.1098/rsbl.2011.1203 (2012)