Eighteen people have died in the Brazilian capital after contracting a hospital superbug.
They were infected with bacteria which produce the enzyme Klebsiella pneumoniae Carbapenemase (KPC), which renders most modern antibiotics ineffective.
It tends to infect hospitalised people whose immune system is already weakened, and those taking antibiotics.
Health officials say 183 people have been infected in Brasilia.
The number of those carrying the bacteria has risen sharply over the past three weeks, but a spokeswoman for the capital's health authority said the increase could be due to more rigorous testing.
A similar outbreak is being reported in hospitals in Chicago, in the United States.
Denise Cardo, an official with the Center for Disease Control in the US, said she had seen an increase in hospital infections in recent years.
"There is no need to panic, but there is a need for a call for action," she told the Associated Press news agency.
The bacteria were first identified in the United States in 1999 and studies suggest they kill 40% of the people they infect.
Brazilian health authorities think that the indiscriminate use of antibiotics could have contributed to the spread of the bacteria.
They said they would bring in new regulations to prevent the sale of antibiotics without prescriptions.