Overuse of Antimicrobial Agents May Contribute to Problems Beyond Development of Resistance

It is well-established that using antimicrobial agents—whether they are drugs, disinfectants, or certain types of pesticides—leads to antimicrobial resistance. Unnecessary use and overuse of these agents exacerbates the issue, which is a major reason why good antimicrobial stewardship practices are so important. However, resistance isn’t the only problem that can result from antimicrobial overuse. Through decades of research, scientists have begun to realize that microbes, both in our environment and in our bodies, play an important role in maintaining our health. This has led experts to consider the effects that implementing “hyper-hygiene” regimens and unnecessary use of antimicrobials may have in addition to development of resistance.  

Microbes in the Environment & Immune System Development

While some microbes pose a threat to human health, the vast majority are benign. Evidence suggests that interactions with microbes help drive immune system development, both during fetal development and in childhood. While reduced exposure to microbes may result in decreased morbidity and mortality in the short term, evidence shows that it may also be associated with a rising prevalence of medical conditions such as allergies, asthma, autoimmune disorders, obesity, and Type 2 diabetes. The reasons for this phenomenon are complex and the subject of ongoing research.

Effects of living in an “over-sanitized” environment were described in a 1989 paper in the British Medical Journal. The “hygiene hypothesis,” as it was termed, attempted to describe the relationship between excessive hygiene practices and the increasing prevalence of certain health conditions, especially in industrialized countries. Newer research suggests that this hypothesis may be insufficient to account for the full range of effects that overuse of antimicrobial agents can have, considering the complex interplay between microbes and our immune systems.

We now know that an array of microorganisms live on our skin and inside our digestive tracts, airways, and other organs, helping with a wide range of functions that we are still learning about, including the immune system. These organisms’ collective DNA is known as the microbiome, and it can be affected by antimicrobial use in the environment and inside our bodies.

Antimicrobial Use & Our Microbiomes

Broad spectrum antimicrobial drugs help treat infections by killing the germs making us sick, but they can also disrupt our microbiomes by wiping out healthy bacteria. For example, studies exploring the long-term effects of antimicrobial use on gut bacteria in adults have found significant alteration of the gut microbiota composition, but there is conflicting evidence on how long these effects may last. In children, exposure to antimicrobial drugs may have long-term effects, which may vary based on factors such as the child’s age. While antimicrobials can be necessary for treating infections in both adults and children, this type of research provides more reasons why it’s important to be judicious in their use.

Antimicrobial Stewardship is for Everyone

Reducing unnecessary use of disinfectants and other antimicrobial agents in our homes and communities is one way we can all contribute to better antimicrobial stewardship and mitigate the adverse effects of overuse. “Early exposure to a diverse range of ‘friendly’ microbes—not infectious pathogens—is necessary to train the human immune system to react appropriately to stimuli,” says an article in PNAS. To maximize exposure to those friendly microbes while reducing risk of exposure to infectious microbes, the author discusses taking a targeted approach to hygiene. “For example, one can teach children to wash their hands after handling raw chicken but also encourage them to play outside in the dirt.”  Additionally, patients can participate in antimicrobial stewardship by following their doctor’s instructions and understanding that antimicrobial drugs are not always needed. Working together, we can reduce antimicrobial overuse that leads to resistance and other adverse health impacts.

Opinions expressed in this article are not necessarily those of bioMérieux, Inc.

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