Researchers found that a harmful bacteria called Enterococcus faecalis, which can be found in contaminated water, is becoming resistant to antibiotics and developing dangerous abilities to stick to surfaces and form protective layers. However, they discovered that beneficial bacteria found in fermented foods like yogurt and kimchi may be able to weaken this harmful bacteria’s dangerous traits. This study suggests that probiotics from fermented foods could offer a natural way to fight these resistant bacteria, though more research is needed before doctors could recommend it as a treatment.

The Quick Take

  • What they studied: Whether beneficial bacteria from fermented foods could weaken the dangerous abilities of a harmful bacteria called Enterococcus faecalis that resists antibiotics
  • Who participated: Eight strains of bacteria isolated from sewage-contaminated irrigation water near Bengaluru, India, plus three types of beneficial bacteria from fermented foods
  • Key finding: Two types of beneficial bacteria from fermented foods significantly reduced the harmful bacteria’s ability to stick to surfaces and form protective biofilm layers (P < 0.0001, meaning this result is very unlikely to be due to chance)
  • What it means for you: Eating fermented foods containing these beneficial bacteria may help your body fight off antibiotic-resistant bacteria, though this is early-stage research and not yet a proven medical treatment

The Research Details

Scientists collected eight different strains of bacteria from contaminated water in India. They tested how resistant these bacteria were to antibiotics and measured their ability to stick together and form protective layers (called biofilms). Then they exposed these harmful bacteria to three types of beneficial bacteria found in fermented foods: Pediococcus acidilactici and Streptococcus thermophilus. They measured whether the beneficial bacteria could reduce the harmful bacteria’s dangerous abilities.

This type of study is called an in vitro study, meaning it was done in laboratory dishes rather than in living organisms. The researchers used standard scientific methods to measure bacterial behavior, including tests for antibiotic resistance, surface stickiness, and biofilm formation.

Understanding how beneficial bacteria can fight harmful bacteria is important because antibiotic-resistant bacteria are becoming a major health problem worldwide. If fermented foods can naturally reduce these bacteria’s dangerous traits, it could lead to new ways to prevent infections without relying on antibiotics that no longer work.

This study was published in a peer-reviewed scientific journal, meaning other experts reviewed it before publication. The researchers used standard laboratory methods and statistical testing to measure their results. However, this was a laboratory study using bacteria in dishes, not a study in humans, so the results may not directly apply to eating fermented foods. The sample size was small (8 bacterial strains), and the study doesn’t tell us whether eating these fermented foods would actually help people fight infections.

What the Results Show

The researchers found that two bacterial strains isolated from contaminated water (called JUSS 05 and JUSS 06) were resistant to the antibiotic ampicillin and showed strong dangerous abilities. These bacteria were very good at sticking to surfaces and forming protective biofilm layers that make them harder to kill.

When exposed to beneficial bacteria from fermented foods, these dangerous traits were significantly reduced. One type of beneficial bacteria called Streptococcus thermophilus (found in yogurt) was especially effective at reducing the harmful bacteria’s ability to stick to surfaces and form biofilms. Another type called Pediococcus acidilactici (found in fermented vegetables) showed consistent ability to break down biofilms across multiple harmful bacteria strains.

The beneficial bacteria appeared to work by producing special substances that interfere with how the harmful bacteria attach to surfaces. This disruption happened in the early stages of biofilm formation, which is when the bacteria are most vulnerable.

The study also found that the harmful bacteria’s ability to stick to surfaces (called hydrophobicity) was directly linked to how thick their protective biofilm layers became. The beneficial bacteria reduced both of these traits, suggesting they work by preventing the harmful bacteria from attaching in the first place. The research also tested these beneficial bacteria against a clinical strain of the harmful bacteria (taken from a patient), and they were still effective, suggesting the results might apply to real-world infections.

Previous research has shown that Enterococcus faecalis is becoming increasingly resistant to antibiotics and is a growing concern in hospitals and environmental settings. This study builds on that knowledge by showing that natural probiotics might offer an alternative approach. While other studies have looked at probiotics fighting harmful bacteria, this is one of the first to specifically examine fermented food-derived bacteria against antibiotic-resistant Enterococcus faecalis from environmental sources.

This study was conducted entirely in laboratory dishes, not in living animals or humans, so we don’t know if eating these fermented foods would have the same effect in your body. The sample size was small (only 8 bacterial strains). The study doesn’t tell us how much fermented food you would need to eat or how long you would need to eat it to see benefits. It also doesn’t test whether these beneficial bacteria would survive the journey through your digestive system or colonize your gut effectively. More research in animals and humans is needed before this could become a medical recommendation.

The Bottom Line

Based on this laboratory research, we cannot yet recommend fermented foods as a treatment for antibiotic-resistant bacterial infections. However, fermented foods are generally healthy and safe to eat as part of a balanced diet. If you are concerned about antibiotic-resistant infections, continue following your doctor’s advice about antibiotic use and food safety. This research suggests fermented foods may have benefits, but more human studies are needed to confirm this.

This research is most relevant to people concerned about antibiotic-resistant bacteria, healthcare providers looking for new treatment approaches, and food scientists developing probiotic products. People with weakened immune systems should consult their doctor before significantly increasing fermented food intake. This research is not yet applicable as a medical treatment for active infections.

This is very early-stage research. If these findings lead to medical applications, it would likely take 5-10 years of additional research before any probiotic treatment could be recommended by doctors. In the meantime, eating fermented foods as part of a healthy diet is safe and may provide general digestive health benefits.

Want to Apply This Research?

  • Track daily servings of fermented foods (yogurt, kimchi, sauerkraut, kefir, miso) and note any changes in digestive health or infection frequency over 3-6 months
  • Add one serving of fermented food to your daily diet (such as a small bowl of yogurt, a few spoonfuls of sauerkraut, or a glass of kefir) and monitor how you feel
  • Log fermented food intake weekly, track any digestive symptoms, and note any infections or illness episodes to see if patterns emerge over time

This research was conducted in laboratory conditions and has not been tested in humans. It should not be used as a basis for treating or preventing infections. If you have a bacterial infection, consult your healthcare provider for appropriate medical treatment. While fermented foods are generally safe and healthy, people with compromised immune systems, severe allergies, or certain medical conditions should consult their doctor before making significant dietary changes. This article is for educational purposes only and does not constitute medical advice.