Posts Tagged ‘antibiotic resistance’
By: Amy Kullas, PhD
On September 21, 2016, the United Nations (UN) convened a special session to discuss options to stop (or at least slow) the emergence of new resistant microbial strains to the precious antibiotics that are still left. This meeting was only the fourth time in UN history that it has convened prominent global leaders to discuss a health related topic (HIV, non-communicable diseases, and Ebola were the others). During this assembly, the group agreed to tighten regulation of antimicrobials, and encourage development of new antibiotics and treatments.
The development of new antibiotics has not been keeping up with the demand. In the United States, pharmaceutical companies have lost interest in developing new treatments. In fact, the most recent ‘new’ class of antibiotics was developed more than 30 years ago, in 1984. Pharma argues that it costs too much money (estimated at $1 billion and takes an average of a decade) to develop a product that will ultimately fail. Without changes in current policies to combat antimicrobial resistance, an estimated $100 trillion could easily be spent by 2050. Hopefully, this attitude may begin to change as the US government’s Biomedical Advanced Research and Development Authority (BARDA) announced to invest up to $170 million to support antibiotic development.
Antibiotics were once hailed as “wonder drugs” since they were virtually effective against every pathogen encountered. Nowadays, what used to be common infections and easily treated with routine antibiotics are now resistant. Moreover, this is a worldwide problem. Using metagenomic analysis, scientists have isolated DNA from soil samples from around the globe and identified the presence of antibiotic resistance genes on all seven continents.
Why has there been this increase in antibiotic resistance? The answer is multifaceted. First, many times when people go to the doctor’s office, they expect to be given a prescription for some drugs to ‘help them feel better.’ Physicians may not wait for cultures to be taken and have the results in hand before prescribing a medication. Thus there is the strong possibility that what is ailing them is a viral infection, such as the common cold, rather than a bacterial infection and antibiotics are ineffective against viruses. It is estimated than almost a third of antibiotics prescribed in the United States are not needed and not effective. Further, the prescription may be for a broad-spectrum antibiotic used to kill many pathogens, as compared to a narrow-spectrum antibiotic that would have a higher specificity for a specific type of bacteria. Use of narrow-spectrum antibiotics is less likely to cause resistance. Also, once the patient begins to ‘feel’ better, he or she may not finish the entire regimen of the prescribed medicine. This likely will leave behind bacteria that have been exposed to the specific antibiotic only to be stronger the next time the microbe encounters it. Other times, people may not even seek medical attention and purchase antibiotics over the counter or online. This practice is becoming common in India and as a result the country houses “some of the most resistant bacteria in the world.”
Additionally, antibiotics and antimicrobials are routinely used in agriculture and are given to livestock (cattle, pigs, poultry, etc.) in their feed or drinking water, and sprayed on crops. Shocking estimates are that over 50% (other estimates are as high as 70%) of the antibiotics in the United States are used in food production. This equates to a whopping 25 million pounds of antibiotic products used on livestock each year! They are given for a variety of reasons: to use less food to gain weight while helping the animal gain weight faster, and of course the treatment, control, or prevention of diseases. Many scientists feel that this heavy use of antibiotics in agriculture is contributing to the rapid increase in antibiotic-resistant bacteria. In China, one study found antibiotic resistance genes present in the manure at pig farms that routinely used antibiotics was increased 28,000 times when compared to farms that do not use antibiotics. More than 60 different antibiotics have been isolated from randomly taken samples from both the Yangtze and Pearl Rivers. Thus, the correlation between antimicrobial use in food production and the significant increase in bacterial resistance has prompted a reexamination of agricultural practices in numerous countries, including the U.S.
The CDC stated “up to half of antibiotic use in humans and much of the antibiotic use in animals is unnecessary and inappropriate and makes everyone less safe.” On the CDC’s urgent list of resistant bacteria are: Clostridium difficile (C. difficile), Carbapenem-resistant Enterobacteriaceae (CRE) and drug-resistant Neisseria gonorrhoeae (cephalosporin resistance). The last-line antibiotics are beginning to fail against these pathogens. Recently, there has been a cluster of gonorrhea cases reported in Hawaii in which the bacteria demonstrated high resistance to azithromycin and reduced susceptibility to ceftriaxone. Physicians are prescribing these two drugs in combination in an attempt to slow the emerging resistance of this relentless microbe. Scientists remain concerned that gonorrhea may soon be resistant to all antibiotics. Even one of the most prominent hospitals in the nation, the National Institutes of Health’s Clinical Center, suffered an outbreak in 2011 of Carbapenem-resistant strain of Klebsiella pneumonia that quickly spread beyond the intensive care unit, ultimately killing six of the patients.
These resistant pathogens have been coined the nickname “superbugs”. However, these superbugs are not nearly as cute as one may envision – little single-celled organisms wearing capes to fight crime. They should be the ones considered criminal, costing billions of dollars annually and killing almost a million people. Advocates and public health experts have been warning of the superbug emergence for decades, but these warnings mostly fell on deaf ears. Last year, the Obama administration revealed a national plan to tackle superbugs and established a presidential council to reduce antibiotic-resistant bacteria. Now for the first time, world leaders finally met to discuss this emerging problem. Hopefully, it is not too late and this global threat will not continue to grow logarithmically out of control.
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