Antibiotic misuse has massively exacerbated the development of antibiotic resistance (ABR). Exposing bacteria to antibiotics risks the bacteria developing genes proving mechanisms of resistance such as the ability to produce antibiotic degrading enzymes, develop an efflux pump which removes antibiotics from the bacterium, and modifying of the molecular target of antibiotics, thus preventing the antibiotic from binding.
As a result, the surviving bacteria become what are commonly referred to as “superbugs”, capable of causing infections which can survive and grow in the presence of antibiotics. These drug-resistant bacterial infections claim at least 700,000 lives worldwide each year, expected to rise to 10 million per year by 2050, if current trends continue, equating to a worldwide GDP loss of $100 trillion over this time frame.
In the most recent attempt to limit the development of antibiotic resistance, the FDA announced on January 3 (2017) that they have implemented new guidelines limiting the use of antibiotics in livestock. These guidelines prevent the use of antibiotics in promoting the growth of livestock and require that new drug applicants confirm that their drug will only be used in livestock in accordance with veterinarian authorization.
When tested in rats it was noticed that those rats given antibiotics gained weight at a significantly faster rate than those not given antibiotics. Consequentially, it became common practice for farmers to give livestock low-dosage antibiotics to promote weight gain. This increases the likelihood of bacteria being exposed to antibiotics and surviving, drastically exacerbating the chances of the bacteria developing ABR. These drug-resistant bacteria are then capable of passing their resistance genes to other bacteria (including other strains of bacteria) through horizontal or vertical gene transfer and are capable of spreading from livestock to humans.
Misuse in livestock constitutes a significant portion of the overall problem of antibiotic misuse, with as much as 80% of antibiotics prescribed in the US being given to animals and an estimated 20% of drug-resistant infections being caused by bacteria from animals/food. The new FDA guidelines will positively impact on the rates of ABR however as outlined by The Guardian and The Natural Resources Defence Council, the guidelines do not restrict the use of antibiotics in livestock disease prophylaxis. Veterinarians commonly prescribe antibiotics to entire farms (up to 5,000 animals) to prevent disease as they go through a facility, and it is common for large quantities of animals to be given antibiotics when a single animal becomes sick. It is therefore questionable whether the new guidelines go far enough in restricting the use of antibiotics in livestock.
Furthermore, antibiotics are misused in various ways in humans. For example, antibiotics are commonly prescribed for viral infections (for which they have no efficacy against) and are commonly terminated when the patient’s symptoms subside rather than on completion of the course, increasing the chances of bacteria surviving. The FDA and the CDC have made previous efforts to raise awareness of this issue, providing guidance on the correct use of antibiotics however this misuse remains an important problem. Animals must come into contact with humans for the drug-resistant bacteria to spread to the human population. It is therefore more common for drug-resistant bacteria to spread from human to human. This is particularly likely in hospitals which are the most common source of methicillin resistant Staphylococcus aureus (MRSA) infections. There is still a pronounced need to further reduce antibiotic prescribing.
Vaccination schedules are used in many countries and also aid in the fight against AMR by preventing bacterial infections ever occurring, eliminating the need for treatment with antibiotics. Finally, recent and forthcoming developments within the antibacterial drug market include several new drugs which are effective in treating drug-resistant bacterial infections, some of which are suggested to possess natural protection against bacterial resistance due to having multiple mechanisms of action. Between, 2000 and 2010 antibiotic use has increased in many regions of the world, particularly within Africa, the middle-east and South Asia.