Antimicrobial agent

An antimicrobial agent is any substance, natural or man-made, that will attack and kill or weaken microorganisms that threaten the life or health of a person or animal. This is done without causing any significant harm to the host.

Antimicrobial agents vary depending on what microbe is being treated and where it is located while it is being treated. Some antimicrobials are used on objects and surfaces, and are regarded as pesticides. Others are used to prevent or treat diseases in humans and/or animals and are considered to be drugs or antiseptic agents. These may be ingested as medicines or foods, or used topically by spreading or wiping on the skin. They are an important key to maintaining health in people and animals, but can and have been overused in some instances.

Background

The word antimicrobial is assembled from several Greek words. Anti, which means against, mikros, which means "small," and bios, which means "life." It is similar to another familiar word, antibiotic. Sometimes the two words are used interchangeably, but this is not accurate. Antibiotics are an example of antimicrobials, but not all antimicrobials are antibiotics. Antibiotics are produced by one organism to work against a second organism. This fits the definition of an antimicrobial because it is a natural substance that attacks another microorganism, but antibiotics always come from a microorganism, while antimicrobials can be natural or synthetic (man-made).

Antimicrobial agents work against a variety of different types of organisms, including viruses, fungi, protozoa, and bacteria. Agents that work against bacteria—known as antibacterial agents—make up the largest percentage of antimicrobials. The first antimicrobial to be discovered was an arsenic-based agent known as Salvarsan. It was synthesized by Paul Ehrlich (1854-1915), a Polish-born German scientist who developed it as a treatment for syphilis in 1910. In the 1930s, compounds known as sulfonamides were created by several scientists. However, both these and Salvarsan were either limited in their usage or had issues with safety and effectiveness.

The first widely used antimicrobial was an antibiotic found by Scottish scientist Alexander Fleming (1881-1955). Fleming discovered penicillin in 1928 when he noticed that mold that had inadvertently grown on a petri dish full of bacteria had killed the bacteria closest to it. Penicillin saved the lives of countless people, including many who were injured during World War II. This discovery set the stage for new antimicrobials, each with new traits that worked better or worked against more types of microorganisms.

Overview

Antimicrobial agents are grouped in categories according to how many types of microbes they are effective against. Narrow spectrum agents work on just a few types of microbes, intermediate spectrum agents work on moderate numbers of microbes, and wide spectrum agents work on many microbes. While using a wide spectrum agent that can attack as many organisms as possible may seem to be a good idea, this is generally not the case.

Many microorganisms possess an ability to adjust and change in response to their environment, including the presence of antimicrobial agents. When this happens, the microorganism becomes resistant to the agent. This means the agent becomes less effective or ineffective against the microorganism. This allows the disease caused by that organism to continue to grow and even spread. Therefore, it is important for physicians to choose the right agent to treat a condition.

It is also important for people to not overuse antimicrobial agents. The frequent use of products such as antibacterial soaps and gels has allowed some forms of microorganisms to develop a resistance to them. Using too many of these products can also interfere with the body's ability to develop its own natural defenses against certain microbes. As a result, the US Food and Drug Administration (FDA), which regulates items that are consumed or used on the bodies of humans, issued new guidelines in 2013 for manufacturers that include these agents in their products, such as soaps and cleaning products. The guidelines require the companies to prove that their products are both safer and more effective than plain soap and water or remove the antimicrobial agents.

This has become an issue because a number of very dangerous microbes have developed resistance to at least some of the available antimicrobial agents. These resistant microbes include Staphylococcus aureus, which causes conditions known as MRSA and VRSA, Streptococcus pneumoniae, which causes a condition referred to as PRSP, and Haemophilus influenza, which results in a condition known as BLNAR. Each of these microbes are relatively common, increasing the risk of contracting one of these illnesses.

Because of the potential issues of antimicrobial resistance and because some of these agents are in and of themselves harmful to humans and animals, they are overseen by either the FDA or the Environmental Protection Agency (EPA). The FDA has jurisdiction over those agents that are consumed or used directly on the human body, such as medications, soaps and body washes, and antibacterial wipes for hands. Products that are used for cleaning surfaces are regulated by the EPA because they are considered to be pesticides, even though the pests they kill are microscopic in size.

The EPA regulates three main categories of surface cleaning products based on their strength and usage. The weakest and most common are sanitizers. These often come as sprays, liquids, gels, or wipes, and are used primarily on bacteria. Disinfectants come in the same formats and are effective on bacteria but also work on some viruses as well as fungi. Sterilizers are the strongest form of environmental antimicrobials. They are generally found in liquid or gaseous form and work against bacteria, viruses, fungi, and mold spores. It is important to note that surface cleaning products are not interchangeable with personal care products; for instance, disinfecting wipes intended for use on counters, shopping carts, and other solid surfaces should not be used to clean children's hands.

Bibliography

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