Resistance Fighters: Bacteria Evolve to Withstand Drugs, Limiting Effective Therapies
By Jia Naqvi
SAN FRANCISCO—Eleven days. That is all it took for E. coli bacteria in a lab demonstration to evolve protections against an antibiotic dose 1,000 times more concentrated than previously needed to kill them.
The well-publicized 2016 experiment (see video below) pointed to the problem of ever-growing antibiotic resistance, fed by increased antibiotic consumption by both humans and animals. Such resistance has become a global public health problem in developed and developing countries alike.
The result is that the most commonly used antibiotics against infections such as pneumonia and tuberculosis are becoming ineffective.
“When we started using antibiotics, one in a hundred million bacteria would become resistant. Today, those numbers are one in two million,” said Ramanan Laxminarayan, director of the Center for Disease Dynamics, Economics and Policy, at the World Conference of Science Journalists 2017. He spoke during a 28 October session titled “Antibiotic Resistance: The Next Challenges.”
“We are directing (...) the bacterial evolution of the planet in a way that is uniquely suited to kill humans.”
Ironically, improved access to health care, thanks to rising incomes, is a contributing factor. Another major contributor is the frequent use of antibiotics in livestock to limit disease and promote growth.
“We are directing through a random series of uncoordinated actions the bacterial evolution of the planet in a way that is uniquely suited to kill humans,” said Kevin Outterson, executive director of CARB-X, the world’s largest public-private partnership for researching and developing antibacterial drugs.
The most vulnerable
Particularly at risk are babies and older adults. In Delhi, India, for example, almost 16 percent of deaths soon after birth were related to multidrug-resistant bacterial infections, according to a 2016 paper in The Lancet Global Health. Older adults are known to be at high risk of developing post-operative infections.
Dealing with the problem, said Outterson, requires addressing several issues simultaneously: balanced access to antibiotics, preservation of existing therapies and innovation in prevention and treatment strategies.
“We are mopping the floor without turning off the tap.”
But measures to counteract the effects of antibiotic resistance have been stymied by continued use of antibiotics at high levels. Many countries have introduced policies to curb antibiotic use, with little or no effect.
“We are mopping the floor without turning off the tap,” Laxminarayan said.
Despite high levels of antibiotic consumption, infectious disease mortality rates in developing countries in South Asia and sub-Saharan Africa, for example, remain high. High mortality rates will persist in those regions until more attention is paid to public health concerns such as clean water, sanitation and hygiene, Laxminarayan said.
Animals and humans at risk
In industrial nations such as the U.S., where such measures helped suppress infectious diseases even before antibiotics were introduced, attention to agricultural practices is another way to deal with the ongoing problem, said epidemiologist Tara C. Smith of the Kent State University College of Public Health.
Almost two-thirds of antibiotics sold and distributed in the U.S. for use in food-producing animals are important for treating humans, according to a 2015 report from the U.S. Food and Drug Administration.
This level of use puts both animals and humans at increased risk of antibiotic-resistant infections. Certain occupational groups such as swine farmers may be at higher risk than the general population.
In need of data
This was shown in a small 2009 pilot study conducted by Smith and her colleagues in Iowa, the largest pork-producing state. Their results, published in PLOS ONE, showed methicillin-resistant staphylococcus aureus, or MRSA, present at high rates in the nostrils of pigs and swine-production workers. Almost half of the 299 pigs and 20 people studied, respectively, carried the bacteria.
If borne out, these findings would dwarf the MRSA occurrence rates of about 5 percent or lower among U.S. and European healthcare workers—a known high-risk group—according to a 2014 analysis in the journal BMC Infectious Disease.
Scientists should focus more closely on how to reduce the evolutionary pressure on bacteria.
But lack of data makes it difficult to trace sources that spread certain antibiotic-resistant bacteria and identify specific groups that are more at risk than others, the panelists said.
Regardless, said Outterson, scientists should focus more closely on how to reduce the evolutionary pressure on bacteria. His CARB-X initiative funds international research on new vaccines, diagnostic tools and drugs to prevent, identify, and tackle antibiotic resistance.
Jia Naqvi is an undergraduate journalism major at Northwestern University in Qatar, with a deep-rooted interest in health and environment reporting. She interned at The Washington Post, where she wrote about health, science and the environment, and for which she is now a freelance foreign correspondent. Follow her on Twitter @JIANAQVI