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In 1928, Alexander Fleming, a Scottish scientist working at St. Mary's Hospital in London, discovered penicillin, the world's first commercialized antibiotic. This monumental discovery was not only a major medical breakthrough but also a significant milestone in the field of microbiology, forever altering the way doctors and scientists researched, administered, and produced drugs. (Source)

With the discovery of penicillin came the realization that bacteria could be inhibited by substances produced by other living organisms. This groundbreaking discovery led to the development of other synthetic antibiotics, including the class of drugs called sulfonamides, which were first used during WWII to treat bacterial infections in soldiers. (Source)

Between the 1950s and 1970s, drug manufacturers began producing antimicrobial agents for broader applications, including the treatment of respiratory infections, skin lesions, and gonorrhea. In fact, the first uses of broad spectrum antibiotics were not in hospitals but in livestock feed, as farmers hoped to use the drugs to promote faster animal growth. (Source)

Although many life-saving antibiotics have been developed to treat previously incurable infections, the overuse of antibiotics in agriculture and food production has led to an increase in antibiotic-resistant bacteria and the creation of superbugs. In fact, the World Health Organization (WHO) has already deemed this problem a global health emergency — calling it ”one of the biggest threats to global health, food security, and development today.” (Source)

In this edition, we're exploring the history behind broad spectrum antibiotics, also known as yet another reason why you should embrace healthy hygiene habits.

What Are Broad Spectrum Antibiotics, and Why Should I Care?

Broad spectrum antibiotics kill a wide range of microorganisms

Broad spectrum antibiotics are used to treat a variety of bacterial infections and are often prescribed when an infection is hard to identify with standard laboratory tests. Unlike narrow spectrum antibiotics — which are targeted to specific bacteria — broad spectrum antibiotics are more indiscriminate in the microorganisms they kill. The unintended negative consequence of this is that broad spectrum antibiotics can lead to an imbalance in the gut microbiota, which is believed to be a source of a host of chronic diseases. (Source)

Broad spectrum antibiotics are used in agriculture and food production

Antibiotic use in farming is widespread and is used by the majority of chicken, pork, and beef producers in the U.S. to promote growth, prevent disease, and control the spread of illness. Estimates vary, but reports suggest the amount of antibiotics given to livestock range from 17.8 million to 24.6 million pounds, compared with around 3 million pounds used by humans in medicine. This practice contributes to the emergence of resistant organisms that can infect humans, such as MRSA and C. difficile, as well as bacteria that can infect animals, such as E. coli. (Source)

Broad spectrum antibiotics have been overprescribed for decades

Although broad spectrum antibiotics are effective at fighting a wide range of infections, they're often overprescribed. In fact, the Centers for Disease Control and Prevention (CDC) estimates that approximately 50% of outpatient antibiotic prescriptions are unnecessary (Source). Overuse of antibiotics not only causes antibiotic resistance, there is evidence it may be linked to the development of inflammatory bowel disease, cancer, and obesity. (Source, Source, Source)

Broad spectrum antibiotics promote the rise of superbugs

Overuse and misuse of antibiotics in the treatment of humans, animals, and food has contributed to the rise of antibiotic-resistant bacteria and fungi. According to the CDC, each year in the U.S. at least 2.8 million people become infected with pathogens that are resistant to antibiotics and at least 35,000 people die as a direct result of these infections. Of great concern are Gram-negative bacteria that cause serious infections and are inherently drug-resistant.The agency has identified 18 bacteria and fungi of concern because they are becoming resistant to nearly all drugs that would be considered as treatment options. (Source, Source)

What is Antibiotic Resistance?

Antibiotic resistance refers to the ability of bacteria and fungi to withstand exposure to antibiotics. According to the CDC, there are a number of ways pathogens become resistant to treatment, including: 

  • Finding ways to block antibiotics from entering cells
  • Producing pumps to remove antibiotics that have entered cells
  • Using enzymes to destroy antibiotics
  • Blocking antibiotic access to the cell parts they target
  • Finding ways to function without the cell parts antibiotics target

(Source, Source, Source)

broad spectrum antibiotics resistance process

What Does the Research Show About Broad Spectrum Antibiotics?

Broad spectrum antibiotics can disrupt the gut microbiome

Research suggests broad spectrum antibiotics can significantly reduce the diversity of your gut microbiome, leaving pathogens to multiply. In one study, subjects given a mixture of three powerful antibiotics lost virtually all their normal microbiota and had overgrowth of pathogenic ones. The participants went on to recover most of their normal microbiota within about six weeks, but after six months, they were still missing nine species of bacteria known to be beneficial. A loss of microbial diversity is thought to be associated with an increased incidence of intestinal permeability and inflammation, including conditions like dysbiosis and leaky gut. (Source, Source, Source, Source)

Narrow spectrum antibiotics may be just as effective in certain cases

Researchers are beginning to look at and compare the differences in outcomes between usage of broad spectrum and narrow spectrum antibiotics. A study published in the Journal of the American Medical Association (JAMA) found that narrow spectrum antibiotics such as amoxicillin were just as effective as broad spectrum alternatives for treating acute respiratory tract infections in children, and had fewer side effects as well. (Source)

Broad spectrum antibiotics may affect immune response to flu

Although research is ongoing, scientists have found that broad spectrum agents may alter individuals’ responses to vaccines. One study found that people with low pre-existing immunity to influenza had a diminished antibody response to an H1N1 vaccine after taking broad spectrum antibiotics than those who did not. Antibiotic-induced alterations to the gut may be the culprit here, as the microbiome protects against infection through its barrier function and immune-stimulating properties. (Source)

They may be associated with the development of IBS

Research shows broad spectrum antibiotics may actually worsen irritable bowel syndrome (IBS) and other intestinal symptoms. One study suggests the use of broad spectrum antibiotics may contribute to the development of IBS by allowing overgrowth of pathogenic bacteria and yeast. The results of this review study are not conclusive, however, and more research is needed. (Source)

What Should I Do About Broad Spectrum Antibiotics?

Use broad spectrum antibiotics sparingly

In addition to negative effects on the gut microbiome, broad spectrum antibiotics are also associated with a number of other side effects, including diarrhea, thrush (yeast overgrowth), and increased risk of C. difficile infection (a potentially fatal gastrointestinal disease associated with antibiotic use). Of course, antibiotics can be life-saving when used at the right time. The key is to only take them if they are truly necessary, so if your health care provider suggests antibiotics, ask if there’s an alternative before filling your prescription. 

Opt for narrow spectrum antibiotics when possible

Narrow spectrum antibiotics may be a better bet to reduce the risk of side effects. They’re more targeted, which means they kill off fewer friendly bacteria and therefore might not disturb your gut microbiome as much. For example, clindamycin is a broad spectrum antibiotic that may be prescribed for staph and strep skin infections, but narrow spectrum antibiotics such as benzylpenicillin (penicillin G) and erythromycin are likely to be at least as effective on these common Gram-positive bacteria and are less likely to cause C. difficile-associated colitis. (Source, Source)

Practice good hygiene habits

Incorporating hygienic habits can protect you from infections and help stop germs from spreading. The CDC recommends a few key tips to keep in mind:

  • Get recommended vaccines
  • Keep hands and wounds clean
  • Manage chronic conditions, like diabetes
  • Prepare and store food safely 
  • Wash hands thoroughly after touching or feeding animals 


Consider supplementing with probiotics or butyrate

One way to deal with the collateral effects of broad spectrum antibiotics may be to replenish your gut with beneficial bacteria, or probiotics, after the treatment. However, while some studies have shown probiotics reduce the incidence of antibiotic-associated diarrhea, others have found probiotics may delay re-establishment of normal microbiota after antibiotic use. As an alternative, butyrate, a short-chain fatty acid (SCFA) produced by beneficial bacteria in the gut, has been shown to inhibit the growth of pathogenic microbes, encourage growth of helpful bacteria, reduce inflammation and promote gut barrier integrity when taken as a supplement. Although supplementation is popular and likely safe for most people, it’s best to consult with your health care provider if you’re considering taking them. (Source, Source, Source, Source)

What Are the Potential Side Effects of Broad Spectrum Antibiotics?

Broad spectrum antibiotics are prescribed to patients suffering from a wide range of bacterial infections. However, in addition to killing the harmful bacteria, broad spectrum antibiotics also kill off the helpful bacteria in your gut.

Some of the most common side effects of antibiotic therapy include:

  • Skin rashes
  • Nausea
  • Vomiting
  • Yeast infections
  • Diarrhea
  • Allergic reactions


Where Can I Go to Learn More About Broad Spectrum Antibiotics?

To learn about the most problematic bacteria

In 2019, the CDC assembled the “Threats Report” to create a reference for key information on antibiotic resistance, including bacteria and fungi of concern ranked based on threat level. Pathogens featured on the list include drug-resistant bacteria that spread in healthcare settings, including Methicillin-resistant Staphylococcus aureus (MRSA), and food-based pathogenic bacteria, like Salmonella. (Source)

On promising alternatives to broad spectrum antibiotics

Given the risks of routine antibiotic usage, researchers are continuing to explore new potential therapies to replace antibiotics. This article digs into some of the alternatives, including bacteriophage therapy, predatory bacteria, competitive exclusion of pathogens, and immunotherapeutics. Many of these types of antimicrobial therapy operate similar to narrow spectrum antibiotics in that they only target the disease-causing pathogens and spare the commensal bacteria; however, unfortunately none of these treatments have consistently shown the same efficacy as antibiotics. 

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We're exploring the history behind broad spectrum antibiotics, also known as yet another reason why you should embrace healthy hygiene habits.
Medically Reviwed
Medically Reviewed by
Stephanie Klein
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