NDM-1, an enzyme that turns bacteria into superbugs resistant to antibiotics, has been confirmed in four patients in South Korea. ((CBC))

South Korea confirmed two more cases of a new gene in bacteria that turns them into drug-resistant superbugs, bringing the total number of cases to four.

The state-run Korea Centers for Disease Control and Prevention said experts detected the gene, known as NDM-1, in two South Korean men on Monday. The country reported its first two cases last week.

Centre official Park Young-un said Tuesday the patients have been hospitalized for a long time and have not travelled abroad.

Park said all four are in the same hospital, which he couldn't name.

The gene appears to be circulating widely in India.