A rare gene from a dangerous antibiotic-resistant bacterium is becoming more common by being transferred between strains, and seems to boost virulence in skin and respiratory infections.

Yuan Lu at Fudan University in Shanghai, China, and Michael Otto at the National Institute of Allergy and Infectious Diseases in Bethesda, Maryland, and their colleagues studied the gene — called sasX — which was recently discovered in methicillin-resistant Staphylococcus aureus (MRSA). They found that sasX encodes a cell-surface protein that helps the bacterium to cling to human nasal cells and to evade the immune system. Mice infected with sasX-positive bacteria developed larger skin abscesses and more severe lung inflammation and tissue damage than animals infected with bacteria engineered to lack sasX.

The SasX protein could be a target for new drugs to combat MRSA, the authors suggest.

Nature Med. http://dx.doi.org/10.1038/nm.2692 (2012)