Asian outbreaks of a notorious antibiotic-resistant super-germ are being driven by a gene that helps the bug colonise the nostrils, lungs and skin and evade the immune defences, scientists said on Sunday. So-called methicillin-resistant Staphylococcus aureus (MRSA) is a major worry for hospitals because of its ability to hole up in wounds, tubes and surgical devices, infecting patients whose immune system is already weak.