as ‘superbugs’ strengthen, an alarming lack of new weapons to fight them....
Posted by
x (aka dmuck)
Dec 15 '16, 06:43
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"For nearly two years, a killer stalked the patients of Providence Alaska Medical Center.
It was a bacteria called Acinetobacter baumannii, a common cause of infections in hospitals. This one was different.
After a rash of mild cases in early 2011, doctors began seeing highly drug-resistant infections in patients, said Dr Megan Clancy, an infectious-disease specialist at the Anchorage, Alaska, hospital. And the bacteria was attacking more patients than just the severely ill ones who are the usual victims of drug-resistant “superbugs.”
Clancy took emergency measures. Infected patients were isolated. Staff and visitors had to adhere to strict hand-washing and other infection-control protocols. Furniture and equipment were scrubbed to remove a microbe that can stubbornly persist on all sorts of surfaces.
Clancy also contacted outside researchers for help. They found that a strain of the bacteria had acquired a rare combination of traits. Bacteria typically are either highly resistant to drugs or highly virulent. This strain was both.
Doctors quickly burned through the antibiotics used as the second and third lines of defense against superbugs. This strain shook them off.
“When you start running out of medications, it gets pretty desperate,” Clancy said.
Eventually, they turned to colistin. This powerful antibiotic was largely abandoned in the 1960s for its toxic side effects. Out of necessity, it has become in recent years a weapon of last resort against the worsening superbug scourge.
But in some of the Alaska cases, even colistin didn’t work. For public health officials, that’s the nightmare scenario.
“It’s the worst of all possible worlds: You have a bacteria that is good at establishing infection, and it can’t be treated with antibiotics,” said Dr Robert Clifford, a microbiologist at the Walter Reed Army Institute of Research who studied the outbreak.
In early 2013, the infections stopped as mysteriously as they had begun. By then, the virulent strain had infected 19 patients and contributed to the deaths of five of them. A sixth died after contracting another highly resistant A. baumannii strain.
The Alaska outbreak, and others like it that make headlines with increasing frequency, illustrate a major weakness in the fight against superbugs: The arsenal of antibiotics is nearly empty. And significant financial and legal hurdles are getting in the way of the already challenging process of discovering effective new ones.
It’s been 30 years since the discovery of a new class of antibiotic that has hit the market. Each class is defined by its chemical structure, which determines how it kills bacteria. The longer an antibiotic is in use, the more time bacteria have to develop resistance to it. Penicillin and its ilk date back to World War Two, and resistance to this group is now widespread, as it is becoming for other extant classes.
Thirty-seven antibiotics are currently undergoing clinical trials, according to the Pew Charitable Trusts, which keeps track of the U.S. pipeline. Most, however, are based on existing drugs. While these derivatives are cheaper and easier to develop than new classes of drugs, bacteria have a head start in developing resistance to them.
Further, most drugs in the pipeline target so-called Gram-positive bacteria, a group that includes the well-known superbug methicillin-resistant Staphylococcus aureus (MRSA). But recently, the main emerging threats have come from the group known as Gram negatives, which are harder to treat because they are encased in tough membranes that repel many drugs. Among them: the lethal Acinetobacter that hit the Providence Alaska Medical Center."
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