A drug-resistant "superbug" has infected three Australians who travelled to India, an expert said on Friday, reinforcing fears it could spread worldwide after hitting dozens of people from Britain.
Professor Peter Collignon, Canberra Hospital's head of infectious diseases department, said the cases -- including one patient who had plastic surgery in Mumbai -- were just the "tip of the iceberg".
"There may well be more because it's difficult to pick up this particular gene unless you've got sophisticated testing," Collignon told AFP.
British scientists sparked an angry response from India when they said "medical tourists" to the sub-continent were among 37 people who were found to be carrying bacteria with the New Delhi metallo-lactamase-1 (NDM-1) gene.
"We strongly refute the naming of the enzyme... and also refute that hospitals in India are not safe for treatment including medical tourism," the Indian health ministry said in a statement.
The gene was identified last year in bacteria carried by a Swedish patient admitted to hospital in India.
The gene, which is found in a number of different bacteria, produces an enzyme that renders even very strong, last resort antibiotics ineffective in combating the bacteria.
Collignon said he treated one of Australia's three cases in Canberra, while there was one each in the eastern states of New South Wales and Queensland.
"We found this multi-resistant, untreatable bug in their urine, luckily not causing too many problems to that person. But it's a real problem if it spreads to others," he said.
"The germ we had was untreatable -- there were no drugs we had that could treat it," he added.
Collignon said his patient caught the bug in intensive care in an Indian hospital after plastic surgery went wrong. But he said one of the three picked up their bug in the general community, indicating the extent of the problem.