Washington, Feb 19 (IANS) A dangerous and under-recognized superbug is targeting the young and healthy in the US, being a much more potent variant of a common bacterium known as K penumoniae.

"Historically, classical strains of Klebsiella pneumoniae have caused infections mostly in sick, hospitalized patients whose host defence systems are compromised," says Thomas Russo, professor of medicine at the University of Buffalo School of Medicine.

"But in the last 10 to 15 years, a new variant of it has begun causing community-acquired infection in young, healthy individuals," he says, the journal Public Library of Science ONE reports.

"This variant causes serious, life-threatening, invasive infections and is able to spread to other organs from the initial site of infection," adds Russo, according to a Buffalo statement.

Perhaps most important, says Russo, these hypervirulent strains of K pneumoniae have the potential to become highly resistant to antibiotics, similar to E coli and classical K pneumoniae.

"These hypervirulent strains are the next 'superbugs' Â-in-waiting," he says. "If they become resistant to antibiotics, they will become difficult, if not impossible to treat."

Russo and his colleagues are studying the microbiology of the new variant in an effort to identify the genes that make it hypervirulent so they can figure out how to stop it in its tracks.