A family of bacteria that is responsible for most hospital-associated infections appears to be on its way to achieving antibiotic resistance.

A recent study shows two genes that play a major role in resistance against a strong class of antibiotics, called carbapenems, can be easily shared among a family of bacteria that recently infected several patients at two Los Angeles hospitals, according to the Washington University in St. Louis. The bacteria were believed to have been spread through the use of contaminated medical scopes. These types of infections are not always fatal for healthy individuals but are extremely dangerous for patients with weakened immune systems.

"Carbapenems are one of our last resorts for treating bacterial infections, what we use when nothing else works," said senior author Gautam Dantas, associate professor of pathology and immunology. "Given what we know now, I don't think it's overstating the case to say that for certain types of infections, we may be looking at the start of the post-antibiotic era, a time when most of the antibiotics we rely on to treat bacterial infections are no longer effective."

Researchers looked at a family of bacteria called Enterobacteriaceae, which includes E. coli, Klebsiella pneumoniae and Enterobacter. They also studied two genes responsible for carbapenem resistance. The first was KPC, which was first detected in New York in 2001, and spread around the world, excluding some South Asian countries. The second was NDM-1, which was identified in 2006 in New Delhi, India, and spread throughout South Asia. They analyzed the genomes of carbapenem-resistant bacteria isolated in the United States and compared them with carbapenem-resistant bacteria isolated in Pakistan. 

The researchers expected to see significant genetic differences between the two genes, which would explain why they had remained exclusive. To their surprise, the findings revealed strong genetic similarities between the two genes.This suggests the antibiotic resistance held in the genes could be shared easily among bacteria from both regions.

"Our findings also suggest it's going to get easier for strains of these bacteria that are not yet resistant to pick up a gene that lets them survive carbapenem treatment," Dantas said. "Typically, that's not going to be a problem for most of us, but as drug-resistant forms of Enterobacteriaceae become more widespread, the odds will increase that we'll pass one of these superbugs on to a friend with a weakened immune system who can really be hurt by them."

The findings were reported in a recent edition of the journal Emerging Infectious Diseases.