Post-antibiotic era has already arrived
‘[A] signal we’re headed for trouble’
The threat of a post-antibiotic era — when once treatable infections are impervious to all available drugs — is typically evoked as some future specter to force present change. In reality, at the very narrow margins, it is already here.
“We do talk a lot about a post-antibiotic era as a day soon approaching, but I will tell you that the day is here,” says Arjun Srinivasan, MD, associate director for HAI prevention at the Centers for Disease Control and Prevention. “There are patients in hospitals in this country that have infections with bacteria that we cannot treat with any of the antibiotics that we have currently available to us. These infections are rare but they do occur. We are in a post-antibiotic era because we are encountering these infections in some of our hospitals.”
Speaking at a recent conference call and press conference, Srinivasan read a joint statement signed by a diverse new collaboration of partners regarding the critical importance of preserving antibiotic efficacy.
“It’s not just the infectious disease groups who have to lead this charge,” he said. “It has to be a broad coalition of different groups coming together that represent all of the different stakeholders in the problem with antibiotic resistance. It’s not even just clinicians and healthcare representatives, it’s consumers — Consumers Union is a signatory to the statement. We believe that this is the first time that such a broad coalition has come together to try and address this problem.”
How did we get here? There is considerable public pressure on physicians — many of them in outpatient settings — to prescribe drugs in what is often an honest attempt to help the sick individual at the ultimate expense of the herd. But too often the antibiotic treatment does not fit the illness, is cut off too quickly, extended beyond periods of clinical need or otherwise used wastefully. The oft cited ballpark estimate is that about half of overall antibiotic use is unnecessary. These critical weapons against bacteria are thrown into the breach like a shovelful of coal into the maw of a steam engine. The result is a selective pressure that kills off susceptible pathogens but leaves multiple-drug resistant organisms in ever greater numbers. Some of them – i.e., the MDR gram negative rods emerging out of Southern Asia — can transfer drug resistant qualities on mobile plasmids to other bugs. As a result, pathogens may acquire resistance to antibiotics they were not actually ever exposed to in a traditional clinical sense.
And it goes well beyond health care. Antibiotics are given to farm animals in mind-boggling amounts that must be totaled up in year-end tonnage. “About 30 million pounds of antibiotics are sold for animal use — about 7 million pounds [are] sold for human use,” said Gail Hansen, DVM, a veterinarian and senior officer at the Pew Charitable Trusts in Washington, DC.
“We know that the antibiotics that are sold in this country for food-animal use far outstrip the amount sold for human use,” she added. The Food and Drug Administration is planning to implement a voluntary policy to bar antibiotic use for animal growth promotion, but “how well that’s going to work remains to be seen,” she said.
“The CDC, the FDA and the USDA have all publicly talked about the fact that giving antibiotics to animals is part of the problem,” Hansen said. “All three agencies have veterinarians involved.”
A similar problem on both coasts
All the while, common infections heretofore cleared by routine therapy are showing signs of resistance to the antibiotics that once sent patients home with a spring in their step.
“For example, the loss of cephalosporins to treat urinary tract infections, which often occurs in the setting of preexisting resistance to other commonly used antibiotics like trimethoprim-sulfa or fluoroquinolones,” said Henry “Chip” Chambers, MD, chief of infectious diseases at San Francisco General Hospital. “[This causes outpatient] clinicians to have to consider the presence of drug resistance, and the possibility that they might have to [hospitalize] a patient to administer parenteral antibiotics. It takes away an oral option. It’s trends like this that signal we’re headed for trouble.”
On the opposite coast, a mirror image appears. “Chip gave a great example because it’s something that we see on a weekly basis in our emergency department,” said Sara Cosgrove, MD, associate hospital epidemiologist at Johns Hopkins in Baltimore. “We have women who end up needing to be admitted for a urinary tract infection. In the past they could just be sent home on an oral antibiotic, but because the infection is potentially resistant to that oral antibiotic that can’t happen anymore.“
Eventually, those individual MDRO patients compound the problem sufficiently that wholesale changes in empiric drug therapy must be considered.
“Once you have a critical threshold reached of enough patients in your hospital having an infection with a resistant organism you have to select [broader] empiric therapy,” Cosgrove said. “They’re presenting ill and we need to give them antibiotics before we get all the [susceptibility] data back. So we have to give broader antibiotics to large numbers of patients because a small number of patients have resistant infections. We don’t know from the get-go whether a patient at a particular time early in [his or her] presentation is going to have a resistant infection, but we don’t want them to get even more ill because we chose the wrong antibiotics. This has led to a trend across pretty much every hospital in the United States that the antibiotics we select for empiric coverage are much broader than they ever used to be.”
The threat of a post-antibiotic era when once treatable infections are impervious to all available drugs is typically evoked as some future specter to force present change. In reality, at the very narrow margins, it is already here.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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