Are viruses the best weapon for fighting superbugs?


David Pride, Associate Director of Microbiology, University of California San Diego

Chandrabali Ghose, Visiting Scientist, The Rockefeller University

via The Conversation - March 6, 2019


Antibiotics won the battle against resistant bacteria, but they may not win the war.


You probably know that antibiotic-resistant bacteria, also known as superbugs, have hampered physicians’ ability to treat infections. You may also be aware that there has been a steep decline in the number of new antibiotics coming to market. Some headlines suggest humanity is doomed by antimicrobial resistance; even politicians and governments have weighed in, comparing rising antimicrobial resistance to other popular crises such as climate change. Although I believe these assertions are exaggerated, antimicrobial resistance is a serious problem.


I am a physician scientist with a specialty in infectious diseases. I have been fascinated by the role that bacteria play in human health, and the potential for using viruses to treat bacterial infections.


What causes antimicrobial resistance?


One significant factor contributing to antimicrobial resistance is the excessive use of antibiotics. In the U.S., where antibiotics are widely available, some patients demand these drugs for many different illnesses. Many physicians appease their patients because they don’t understand when and when not to use them and because there is no regulatory structure to limit their use. Anyone with a prescription pad can prescribe any antibiotic to treat any condition and rarely, if ever, face any consequences. There are some efforts to reduce antibiotic use, but the scope of the problem in the U.S. remains large.


Some countries, such as Sweden, use incentives to encourage doctors to improve antibiotic uses. But there is no counterpart for this system in U.S. hospitals and clinics.


The problem goes beyond humans; 70 percent of all antibiotics are actually used on animals. This means that humans can be exposed to antibiotics by just handling animal products. The drumstick you are preparing for dinner might also have antibiotic-resistant bacteria tagging along.


Once antimicrobial resistance develops in a bacterium, it doesn’t always go away. For example, methicillin-resistant Staphylococcus aureus (MRSA) evolved resistance to multiple different antibiotics; yet, despite efforts to reduce its spread by limiting the use of antibiotics that led to its emergence, MRSA still persists in hospitals and the community.


An alternative to antibiotics


Another reason for finding alternatives to antibiotics is that we share our microbes with the people and pets who live around us; thus, others can acquire one of these superbugs without ever taking an antibiotic.


A not-so-obvious reason for developing new therapies is that our bodies are home to a large community of microorganisms, including bacteria, called our microbiome. These microorganisms are necessary to maintain our health. Those same antibiotics that kill harmful bacteria also kill the good ones.


There is an alternative to antibiotics, but it was dismissed by medicine years ago.


The original phage therapy story


That alternative was something called phage therapy, which uses viruses that infect bacteria, called bacteriophages, to kill disease-causing bacteria. Bacteriophages, or phages, were used frequently in the early- and pre- antibiotic eras between the 1920s and ‘40s to treat life-threatening infections.


But phage therapy had many disadvantages. The first was that phages were unpredictable. One type of phage might wipe out the bad bacteria in one individual but not another’s. So hospitals had to keep a broad collection of phages to kill disease-causing bacteria from all their patients. An antibiotic such as vancomycin, by comparison, predictably kills entire groups of bacteria.


Another downside is that phage collections require maintenance. So not only did hospitals have to keep a large variety of phages on hand, but they had to keep them in shape. So medicine chose antibiotics for convenience, and hadn’t looked back in any meaningful way, until recently.


Making a comeback? ...


The case for using phages ...


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