Staph Infection: Why Bacteria Cling & How to Fight Back

some microbes can be quite clingy.

Staphylococcus aureus, a bacterial species responsible for staph infections, latches onto human skin with one of the strongest ​biological bonds ever recorded, researchers report in ⁣the Sept. 5 Science Advances. This‍ powerful ⁢grasp is strengthened by the mineral calcium, preventing bacterial cells ⁤from ⁣being washed or brushed away ⁤from ‍skin.

An influx of calcium to damaged‍ skin, such as ⁣a ‍cut or a condition like eczema, is “a ​way of growing your skin faster,” says Rafael Bernardi, a biophysicist at Auburn University in‌ Alabama. But “the ⁤mechanism that ‌we use to fix a bruise is ‌the same ⁤mechanism that the bacteria take advantage of to bind better ⁤to⁣ our ⁤skin.”

A common skin‌ microbe, S. aureus can invade the body through cuts and scrapes to cause skin ​infections such as cellulitis or life-threatening systemic infections when staph spreads to other ‌parts of​ the⁢ body. Disrupting the super strong bond between staph and​ skin could help researchers develop new treatments.

Bernardi and colleagues used microscopy and computer simulations to analyze the molecular⁤ handshake between a bacterial protein called SdrD and a human protein called DSG-1 in lab dishes. In⁣ the presence of calcium, the two proteins could withstand forces stronger than 2 nanonewtons, or 2 billionths of a newton. “We don’t know of any [biological] bond​ that is stronger than this one without a covalent bond,” which is when two atoms share electrons,bernardi says.

Mechanical forces going on inside a cell are typically weaker, measured in no more than dozens of piconewtons ‌(a thousandth of a⁣ nanonewton), Bernardi says. it might take 60 to 80 piconewtons, as ⁢an example, to break apart proteins that help muscles contract. But SdrD and DSG-1 cling together roughly ⁤20 ‌times more strongly. At the molecular ⁣level,tiny ‌bacteria “can grip more than⁢ your muscles can lift,” Bernardi says.

People often⁣ have different strains of staph living on their skin,and it’s unclear if‍ there are variations in binding strength among strains. Still, preventing ​SdrD and DSG-1 from binding could make staph infections easier to treat.

Some antibiotic-resistant strains such as MRSA can form biofilms, a protective, slimy shield that forms⁤ around clusters of bacteria and can make infections harder to treat. But if individual​ cells never attach to skin, Bernardi says, then the biofilm can’t develop, and immune cells, or antibiotics, ​can ⁣swoop in for​ the kill.