Says this article at The Atlantic :
Superbugs like Methicillin-resistant Staphylococcus aureus, or MRSA, have wreaked havoc on the health-care system in recent years. […] How do you stop them? Frequent hand washing is one option, but that requires a behavior change, which can be difficult, even for hospital staff. Another option is to coat those frequently fondled objects most likely to carry the bugs—doorknobs, bed rails, toilet handles—with a special anti-microbial surface, like copper. […] Whitlock found that salt killed off the bug 20 to 30 times faster than the copper did, reducing MRSA levels by 85 percent after 20 seconds, and by 94 percent after a minute.