You know that scene in action movies where the hero has fired every bullet, thrown every piece of throwable furniture, set off every explosive, but still the bad guy lurches forward? At that point, there’s nothing left for the hero to do but run and pray. After the recent discovery in the U.S. of a bacteria that is resistant to a vital last-resort antibiotic, some scientists believe we’re inching dangerously close to that run-and-pray moment in the world of medicine.

“We risk being in a post-antibiotic world,” Dr. Tom Frieden, Director of the Centers for Disease Control and Prevention told reporters yesterday after military researchers confirmed the first-known U.S. instance of the MCR-1 gene, which provides antibiotic resistance to colistin, a drug of last resort. “That wouldn’t just be urinary tract infections or pneumonia — that could be for the 600,000 patients a year who need cancer treatment.”

Added Dr. Frieden, “The medicine cabinet is empty for some patients.”

For decades, doctors have treated multi-drug resistant bacteria with a class of antibiotics known as carbapenems. But the more you use a drug, the more the pathogens adapt to survive, so now there are carbapenem-resistant bacteria (CRE). Colistin, a potent antibiotic that had long been shelved because of its potential for kidney damage, has come back into use in recent years as a last-resort treatment for CRE infections.

While the bacteria found this month in the Pennsylvania woman is resistant to colistin and many other antibiotics, it is sensitive to carbapenems. However, now that the MCR-1 gene is stateside, some are very concerned that we’ll inevitably see bacteria that are resistant to both CRE and colistin.

“We are one step away from CRE strains that cannot be treated with antibiotics,” Dr. Lance Price, a researcher at George Washington University, tells the NY Times. “We now have all the pieces in place for it to be untreatable.”

Dr. Beth Bell of the CDC likens this fully resistant superbug to a nearly completed puzzle.

“You need lots of different pieces to get a result that is resistant to everything,” she explains to the Times. “This is the last piece of that puzzle, unfortunately, in the United States. We have that genetic element that would allow for bacteria that are resistant to every antibiotic.”

Bloomberg News today looks at the death of a child in India whose infection could not be treated by colistin.

“That is a warning to us that maybe we’re already losing this drug,” a hospital official tells Bloomberg. “If we lose colistin, we have nothing. It’s an extreme, extreme worry for us.”

Not every doctor is beating the doom-and-gloom drum about this discovery.

University of Pennsylvania hospital infectious disease specialist Neil Fishman tells Philly.com that the news is “not a death star, but a very strong warning that we really do have to be careful with antibiotics and use them optimally.”

While across town, Temple University Hospital specialist Tom Fekete cautions that he’s “not giving up the ship,” and notes that people have been declaring a “post-antibiotic world” for 20 years.

Earlier this month, the Pew Charitable Trusts released a report showing that no new types of antibiotics have been discovered in more than 30 years, raising the concern that resistance — in the absence of new drugs — could wipe out the utility of the ones we’ve been using since the golden ages of antibiotics research in the mid-Twentieth Century.

“This is definitely alarming,” said Pew’s David Hyun about yesterday’s announcement. “The fact that we found it in the United States confirms our suspicions and adds urgency to actions we need to work on antibiotic stewardship and surveillance for this type of resistance.”

The discovery of the MCR-1 gene in the U.S. has resulted in renewed calls for improved antibiotic oversight, particularly in farm animals, who consume the overwhelming majority of antibiotics in the country, primarily for the non-therapeutic purpose of growth-promotion.

“I have been sounding the alarm for years, and now, what we’ve been dreading has happened,” said Congresswoman Louise Slaughter of New York, who also happens to be a trained microbiologist. “We have an antibiotic-resistant superbug that can’t be killed by any known drug. We need swift, aggressive, global action to stop this in its tracks—now.”

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