By Elizabeth Ensink
This fall, the President’s Council of Advisors on Science and Technology released a report calling for greater attention and action on the issue of antibiotic resistance. Since the discovery of Penicillin by Alexander Fleming in 1928, antibiotics have saved millions of lives. Without antibiotics, ear infections, sore throats, and even skin infections from a minor injury could become deadly, not to mention the increased severity of diseases such as pneumonia and meningitis. However, over the years there has been a concerning increase in strains of bacteria that are resistant to these antibiotics. The Center for Disease Control estimates that antibiotic resistant strains of bacteria cost at least $20 billion in extra health care costs each year. If resistant strains of bacteria continue to thrive and develop, we could be left without our first line of defense against infections.
To understand the growing problem of antibacterial resistance, it is necessary to understand the dynamic nature of bacteria populations. The genomes of bacteria are constantly changing through mutations and horizontal gene transfer, which can sometimes increase the resilience of the bacteria. Common resistance mechanisms in bacteria include using enzymes that degrade the antibiotic drugs, changing the antibiotic’s target or altering the permeability of the bacterial membrane to the drug. When antibiotics are administered, the bacteria that have these resistance characteristics survive and can pass their resistance genes on to their progeny.
Not only do antibiotics lead to increasing antibiotic resistance in the population, they may also disrupt the normal balance of beneficial bacteria in our gut. Scientists have shown increasing interest in research on the gut microbiota. Although the complex relationships between humans and their microbiome are not completely understood, the relationship is clearly important for our health. Some scientists have even begun to apply ecological theory to the community of bacteria living inside us. From this perspective, antibiotics may be viewed as a disturbance similar to a wildfire or hurricane on an ecosystem. Just as chemotherapy cannot always distinguish between cancerous and healthy cells, antibiotics frequently wipe out more than their target bacterial species. This creates a shifted environment in our body with an open niche for pathogenic microbes such as C. difficile to thrive with little competition. Normal ecosystems recover after a disturbance, and our gut microbiota does typically return to normal over a period of time. However, studies have also shown that antibiotic treatment over a longer period of time can lead to significant shifts in the composition of a patient’s microbiota which could have long-term impacts on health.
Despite the danger of antibiotic resistant strains of bacteria and the disruption that antibiotics can cause to our microbiota, physicians continue to prescribe antibiotics as a commonly used option to fight infections. To address this concern on a national level, the PCAST report offers three recommendations. First, they call for increased surveillance of antibiotic resistant bacteria by creating a reference collection of genome sequences of antibiotic resistant strains. They also encourage more informed and careful use of prescribed antibiotics. Finally, they seek increased federal support in the search for new therapies against pathogenic bacteria.
One promising new development in this search is the discovery of compounds that treat infections by targeting the mechanisms behind bacterial pathogenesis. These mechanisms include adherence to cells, evading the immune system, and secretion of toxic molecules. Unfortunately, studies have already shown that bacteria can develop resistance against these treatments.
Antibiotic resistant infections are already highly detrimental to humans. It is unclear exactly how soon antibiotic resistance will develop to a point critical for human welfare, but it is important for the scientific community and general public to take note now and work towards a better understanding of our complex relationship with bacteria.