Although clusters of CRE expressing OXA-48-like carbapenemases suggest transmission has occurred in the United States, the majority of identified patients were reported to have had exposure to health care outside the United States. (The name is an abbreviation for "carbapenem-resistant Enterobacteriaceae," meaning the bacteria are part of a group called Enterobacteriaceae and are resistant to treatment with antibiotics called carbapenems.) They are often deadly, too, in some instances killing up to 50 percent of patients who become infected, according to the CDC.
– The latest strains of antibiotic-resistant bacteria to give researchers sleepless nights aren't the most common—or even the most antibiotic-resistant—but they have an ability that could make them a serious danger to public health. They contain enzymes known as "OXA-48-like carbapenemases" that can break down antibiotics and transfer that ability to normal bacteria in the body through mobile pieces of DNA, reports the Washington Post. and Live Science. The enzymes have been nicknamed the "phantom menace" by researchers because they can be tough to detect. In a report issued this week, the CDC says it identified 43 cases in the US involving the superbug between June 2010 and August of this year, mainly involving people who had traveled overseas, though some cases are thought to have been transmitted in the US. "This is a tricky drug-resistant bacteria, and it isn't easily found," CDC Director Thomas Frieden tells the Post. "What we're seeing is an assault by the microbes on the last bastion of antibiotics." The number of cases is small but rising, Frieden says, warning that what has been detected so far could just be the "tip of the iceberg." An infectious disease specialist tells Live Science that while the bacteria shouldn't be a major worry for the general public right now, doctors and patients should be aware that the best way to combat antibiotic resistance is to try to be more sparing in the use of antibiotics. (A mutation spreading in China has prompted warnings of an "antibiotic apocalypse.")