History of Antibiotics
Antibiotic resistance has been a concern since 1940, twelve years after the introduction of penicillin. Unfortunately, as each new antibiotic is introduced (often in an effort to combat antibiotic resistance), resistant strains appear to emerge soon after.
Examples of antibiotic resistance development include the following:(1)
As you can see, there isn’t always a long delay between the introduction of a new antibiotic and the development of resistant bacterial strains!
Every year, in the United States alone, approximately 2 million people are infected with antibiotic-resistant bacteria; approximately 23,000 individuals die each year as a result of antibiotic-resistant infections.(1) These numbers are expected to become even larger as an increasing number of individuals are prescribed long-term immunosuppressive drugs for organ transplants and other medical conditions.
Antibiotic Resistance Mechanisms
Antibiotic resistance is often a result of the selective pressures that antibiotics exert upon a bacterial population. When an infection is treated with an antibiotic, the bacteria that are most susceptible to the antibiotic are the first to die. When antibiotics are discontinued, small numbers of antibiotic-resistant bacteria may be left behind. In some cases, these bacteria reproduce and proliferate. This leads to an antibiotic-resistant infection, which not only has effects on the infected animal but can also be transmitted to others.
Bacteria can also develop resistance through plasmids. Plasmids are genetic structures, often found as circular pieces of DNA in the cytoplasm of a bacterium or protozoan, that replicate independently of the chromosomes.
These plasmids can be transmitted from one bacterium to another, allowing the spread of antibiotic resistance genes.
Bacteria may use a number of different strategies to resist antibiotics. Examples include:
What laws govern the use of antibiotics in veterinary patients?
In 2017, a series of laws were introduced that require veterinary oversight when medically-important antibiotics (antibiotics that may be used in human medicine) are administered in the feed of a food animal species.(2) Food animal species, in this case, may include cattle, swine, and even honeybees, among others.
Veterinary Feed Directives are intended to reduce the indiscriminate use of antibiotics in food animals. This is seen as an area of concern, because antibiotic-resistant infections in food animals can be readily passed to humans when that food animal is consumed.
Are there guidelines available for small animal veterinarians?
While there are currently no specific laws to prevent antibiotic resistance in small animal patients, there is a movement by various professional organizations towards more responsible use of antibiotics in order to minimize the risk of antibiotic resistance.
The AVMA has developed some general guidelines outlining responsible antibiotic usage in the treatment of common companion animal species.(3) These guidelines are intended to ensure that antibiotics are used only when necessary and that other interventions are considered when appropriate.
Additionally, a number of organizations have released improved guidelines for the selection of appropriate antibiotics for common bacterial infections. These guidelines typically outline appropriate treatment durations, because treating for both insufficient and excessive intervals may encourage the development of resistant bacteria. Urinary tract infections(4), respiratory infections(5), dermatologic infections(6), and others are all covered under published guidelines.
Veterinarians play a valuable role in limiting antibiotic resistance by limiting the prescribing of antibiotics, making thoughtful antibiotic selections, and using appropriate treatment durations.
How can I educate clients about the importance of antibiotic resistance?
When discussing or prescribing antibiotics, look for opportunities to mention the topic of antibiotic resistance. While it’s a topic that all of us in the veterinary profession are familiar with, many clients just don’t think about the topic of antibiotic resistance and the effects that it can have!
Look for opportunities to mention the following items to clients:
References