Antibiotic Practices and the Gut Microbiome

Antibiotic Practices and the Gut Microbiome

September 2, 2023

Joy Stepinski, MSN, RN-BC

Many lifestyle factors contribute to the health of the gut microbiome, like diet, stress, emotions, exercise, and medication. Certain drug classes can change the microbiome, which impacts health outcomes, drug effectiveness, and the patient’s response to the drug itself [1]. Antibiotics have long been known to affect the gut with reports of an upset stomach or diarrhea corresponding with treatment.

The human gut is home to trillions of bacteria, fungi, and other microbes. The community of microorganisms, or microbiome, is dependent upon an ideal environment. The appropriate amount of moisture, pH, temperature, and nutrients [2] are all required for survival. These factors help to maintain a high diversity of bacteria, which is significant for human health and many biological processes within the body.

Humans are widely exposed to antibiotics through medical care and food. When a serious infection is present, antibiotics can be of great necessity. Although these drugs can kill unwanted bacteria, they can also wipe out beneficial organisms, as well. In fact, this is an alarming problem and often discussed among healthcare professionals in the terms of antimicrobial stewardship (see below).

Although historically considered “miracle drugs” (p. 59) [3], antibiotics can have serious ramifications. Among the problems are widespread overuse, including viral respiratory infections (i.e., cold, flu, and bronchitis). Additionally, antibiotics are classified according to the range of bacteria targeted. Broad-spectrum antibiotics, like amoxicillin, kill a wider range of bacteria than narrow-spectrum drugs. Beneficial bacteria are also wiped out. Antibiotics may not be used judiciously and instead prescribed for conditions not necessarily warranted. As a result, disease resistance is a growing problem.

Antibiotics are widely found in food and have been given to feedlots for decades, often for the purpose of enlarging the animals [4]. According to a report published by the National Resources Defense Council (NRDC) [5], antibiotic sales are higher among livestock operations than for human use. Frequently the drugs are given to entire feedlots, even when cattle are not sick. The four major feedlot corporations (Cargill, JBS, Tyson Foods, and National Beef) control over 80% of the meatpacking industry and reportedly have limited policies surrounding antibiotic practices. Additionally, accountability is lacking. McDonald’s, the largest corporate purchaser of beef, has announced policy changes for more prudent practices [6], although other purchasers have not made moves for improvements. This practice has been banned in Europe [7].

Another report called “Superbugs in Stock” released in 2022 [8] analyzed the policies and practices of the top supermarkets. Although grocery stores ultimately have a responsibility to safeguard human health, most of the top 12 chains fail to address antibiotic overuse by meat suppliers (i.e., Aldi, Publix, Trader Joe’s, Walmart, Kroger, Costco, Target). Instead of addressing animal health and well-being, antibiotic practices contribute to resistance. These resistant microbes are then emerging in animal fecal waste, harvested meat, factory farm environment, and in the food supply.

The microbiota has a symbiotic relationship with the body. Depending on the environment, the microbe can be beneficial or harmful. One species, Enterococcus, is a microbe that normally inhabits the gut. However, virulent pathogen strains of this microbe also exist, especially when the bacteria are found outside its intestinal home. They can be responsible for wound infections, urinary tract infections, and endocarditis [9]. Strains are naturally resistant to common antibiotics, such as cephalosporins, macrolides, and sulphonamides, but also becoming resistant to vancomycin, a medication used for intestinal disease. Enterococci is also present in animal intestines, and can contaminate the meat upon slaughter.

One study from Slovenia discovered a high presence of virulent Enterococci strains among meat [9]. The authors relayed that this finding correlates with other studies that show these strains are connected to infective endocarditis (inflammation of the heart lining and valves). According to one author [4], this species accounts for leading infections among patients hospitalized in the ICU.  One can wonder if these infections are due to food contamination.

Antibiotic use is an important aspect of informed care. Medication can be necessary treatment for concerning infections. On the other hand, therapy may shift microbial populations in the gut. This shift can cause extinction of key species needed for health [10], or can lead to a new stable state [4]. The consequences are not known. However, chronic diseases are on the rise with implications for overall health. The imbalance of the gut microbiome has the potential to cause Clostridium difficile (a debilitating infectious diarrhea), and is implicated in other conditions, such as gut disorders (ulcerative colitis, Crohn’s), skin issues, obesity, childhood-onset asthma, colorectal cancer, irritable bowel syndrome, and Parkinson’s disease.

As an informed health consumer, being familiar with the consequences of antibiotics is important to make decisions about your health. Use the medication thoughtfully and weigh benefits against the risk of harm. Sometimes antibiotics are essential, but other times waiting may be ideal. The broader the spectrum, the more potential for beneficial bacteria to be affected. Avoid animal food with antibiotics and minimize organic meat and wild-caught seafood. Consume a high-fiber plant diet to maximize the diversity of the gut microbes. Caring for the gut microbiome is important for your health and well-being!

References:

1.       Weersma, R. K., Zhernakova, A., & Fu, J. (2020). Interaction between drugs and the gut microbiome. Gut, 69(8), 1510-1519.

2.       Berg, G., Rybakova, D., Fischer, D., Cernava, T., Vergès, M. C. C., Charles, T., ... & Schloter, M. (2020). Microbiome definition re-visited: old concepts and new challenges. Microbiome, 8(1), 1-22

3.       Olans, R. N., Olans, R. D., & Witt, D. J. (2017). Good nursing is good antibiotic stewardship. American Journal of Nursing, 117(8), 58 – 63.

4.       Blaser, M. J. (2014). Missing microbes: How the overuse of antibiotics is fueling our modern plagues. Henry Holt and Company, LLC.

5.       Wallinga, D. (2020). Better burgers: Why it’s high time the U.S. beef industry kicked its antibiotics habit. National Resources Defense Council. https://www.nrdc.org/sites/default/files/better-burgers-antibiotics-ib.pdf

6.       McDonalds. (2022). Responsible antibiotic use. https://corporate.mcdonalds.com/corpmcd/our-purpose-and-impact/food-quality-and-sourcing/responsible-antibiotic-use.html

7.       World Animal Protection. (2022). EU bans the routine use of antibiotics in farmed animals. https://www.worldanimalprotection.org/news/eu-bans-antibiotic-overuse-farmed-animals8.

8.       Center for Food Safety. (2022). Superbugs in stock. https://www.centerforfoodsafety.org/files/superbugsinstock2022_70278.pdf

9.       Golob, M., Pate, M., Kušar, D., Dermota, U., Avberšek, J., Papić, B., & Zdovc, I. (2019). Antimicrobial resistance and virulence genes in Enterococcus faecium and Enterococcus faecalis from humans and retail red meat. BioMed research international, 2019.

10.   Cho, I., & Blaser, M. J. (2012). The human microbiome: at the interface of health and disease. Nature Reviews Genetics, 13(4), 260-270.