How quickly antibiotic resistance can spread

By Melissa Healy

July 11, 2016 10:05 AM PT

How quickly can antibiotic resistance spread? Consider the case of a Swedish man who traveled to India in 2009.

While in New Delhi, the man became infected by a strain of Klebsiella bacteria bearing a gene that made it impervious to the antibiotic carbapenem. Microbiologists quickly found the gene in bacterial samples from Mumbai as well.

In the span of just two years, it also turned up in Croatia, Pakistan, the United Kingdom, Canada, Japan and China.

READ: A "slow catastrophe" unfolds as the golden age of antibiotics comes to an end »

“They found it everywhere,” Hanage said. “The cat was not just out of the bag; it had gotten out of the bag, made its way into the hamster cage, and was eating the hamsters.”

Today, the Centers for Disease Control and Prevention estimates that 9,000 U.S. patients per year are infected with carbapenem-resistant bacteria, causing 600 deaths annually.

“We’re always trying to keep one step ahead,” said Harvard infectious disease epidemiologist William P. Hanage, who warned that bacteria has been at this competition far longer than humans. “There are lots of bugs, lots of drugs, and lots of ways that resistance can happen, and they can start overlapping with each other. It’s damnably complicated.”