Streptococcus: A Probiotic Paradox

Written by: Kari Raman, PharmD, RPh
Published May 27, 2023

Streptococcus is a genus of bacteria that are more or less all over the environment, and even within the human body. Specific species within this genus also serve as probiotics, bringing potential health benefits to their hosts, but some cause serious infection, so patients looking for a probiotic supplement should approach them with caution, and consult with their doctor before beginning them as a supplement. 

At the pharmacy, one of the most common infections I see is “strep throat” – caused by this type of bacteria. Strep throat, which is an infection in the throat and tonsils caused by Streptococcus pyogenes, also known as Group A Streptococcus (GAS). This bacterium can cause infections in other parts of the body as well, but when it infects the throat, it causes the condition known as strep throat. People with Strep throat must see a doctor and begin antibiotic treatment – this is a serious condition that can lead to really nasty complications. And if you are taking probiotics and your doctor prescribes antibiotics for Strep throat, talk with your doctor or pharmacist on how to time the dosing of the supplement, or if you should stop taking the supplement while you treat the infection. 

A quick note on how probiotics and bacteria are named – when you see me abbreviating “S.” in this article, that stands for Streptococcus. An example would be S. salivarius M18 – that’s a very specific strain of this bacteria. 

Streptococcus and its paradoxical nature

Similar to Enterococcus, Streptococcus can also be a helpful ally or a potential threat. Its existence in our body can promote gut health, but under certain conditions, it may lead to infections. Due to this dual nature, it is essential to discuss with a healthcare professional before considering it as a probiotic supplement. There are quality supplement brands that have safe strains of this species, but it’s best to talk with a doctor. 

Streptococcus health benefits 

Streptococcus species confer several health benefits, mainly centering around gut health. They play a crucial role in the fermentation process, leading to the production of lactic acid. This lowers the pH in our gut, making it less hospitable for pathogenic bacteria and supporting overall gut health.

Some of the potential health benefits of Streptococcus include:

– Certain Streptococcus species may aid gut and digestive health by reducing inflammation and instances of diarrhea induced by different bacteria, such as travelers diarrhea.

– Some research suggests that Streptococcus species can enhance the immune system, potentially reducing infection rates, although most of the research I’ve seen here is still being done in a petri dish, not on people. I did find a study that I’ll talk about in a bit about how a specific strain may reduce Strep throat, but it’s a small study. 

– There may be possible oral health benefits, but the research is still too early to really know for sure. S. salivarius M18 has shown, in a small study, to help reduce cavities, but again, more research is needed.

S. salivarius and S. thermophilus are two species often used as probiotics. They are included in various fermented foods, such as yogurt, and are also available as dietary supplements. When taken as a probiotic, Streptococcus may boost gut health, reduce inflammation, and bolster the immune system.

What is Streptococcus?

Streptococcus is a group of Gram-positive bacteria typically appearing in chains or pairs due to their mode of division. They are facultative anaerobes, capable of living in environments with or without oxygen. Streptococcus is resilient and can resist harsh conditions, including a broad spectrum of antibiotics, making treatment challenging when infections arise.

Commonly found in the human body 

Streptococcus species exist in various environments and are also a part of the human microbiome. They contribute significantly to gut health and deter the growth of harmful bacteria.

What are the health risks of Streptococcus?

Although Streptococcus may provide health benefits, certain species can cause infections, including pneumonia, meningitis, or strep throat. Symptoms of an infection from this bacteria may include fever, chills, pain, and swelling. 

The robust nature of this bacteria and its resistance to antibiotics often complicate treatment. In severe cases, Streptococcus infections can progress to life-threatening conditions such as rheumatic fever or post-streptococcal glomerulonephritis.

Can probiotics treat or prevent Strep throat?

I came across one research study where a group of children at high-risk of getting strep throat took S. salivarius K12 – a very specific streptococcus probiotic – and it did show evidence of decreasing the likelihood of them getting strep throat. However, this was a tiny study (41 children) and needs to be replicated in much, much larger settings. AND – this is important – the probiotic is NOT an alternative to taking antibiotics. It does NOT treat strep throat. So you still need to follow your doctor’s orders and take antibiotics to fight off the infection, very important!

Streptococcus in our diet 

Streptococcus plays a pivotal role in food production, especially in fermented foods like yogurt and cheese. It is the secret behind the tangy flavor and creamy texture of these foods, thanks to the lactic acid produced during fermentation.

Alternatives to Streptococcus as a probiotic

Several types of bacteria, beyond Streptococcus, have been studied for their potential benefits as probiotics. Here are a few commonly used and well-studied probiotic bacteria:

  • Lactobacillus: This is one of the most common probiotics and can be found in fermented foods like yogurt and certain cheeses. Different species of Lactobacillus can potentially aid in treating diarrhea, lactose intolerance, and irritable bowel syndrome.
  • Bifidobacterium: This genus of bacteria is often included in probiotic supplements and foods. They are a natural part of the gut microbiota in mammals and are thought to help with conditions such as irritable bowel syndrome (IBS), certain types of infection, and lactose intolerance.
  • Saccharomyces boulardii: Although this is actually a yeast, not a bacterium, it’s often used as a probiotic to help treat conditions such as diarrhea and other digestive issues.
  • Enterococcus: As we discussed earlier, some strains of this bacterium are used as a probiotic and can potentially help improve gut health, although other strains can be pathogenic.
  • Escherichia coli Nissle 1917: While most people associate E. coli with food poisoning, certain strains are actually beneficial. One such strain, E. coli Nissle 1917, has been used as a probiotic to prevent and treat various gastrointestinal disorders.

In conclusion – a beneficial probiotic, but approach with caution 

Streptococcus is a genus of bacteria that is widely found in various environments, including the human body. While certain species offer health benefits, others can be pathogenic. To minimize the risk of infections, maintain good hygiene, ensure food safety, and consult your healthcare provider if you experience symptoms of infection. Before using Streptococcus as a probiotic, seek professional advice. When used appropriately, Streptococcus may be beneficial as a probiotic, contributing to overall health and wellbeing.

Image of streptococcus source: By User:Graham Beards – Own work, CC BY-SA 3.0,

Pharmacist Kari Raman

I’m Kari Raman PharmD, RPh, and I am a licensed, practicing pharmacist. I hold a Doctorate in Pharmacy from The University of the Pacific, and I’ve served patients in retail, compounding and hospital pharmacies.

Probiotics are confusing!

One of the most common questions I get asked by patients is about probiotics. And the truth is, probiotics are not as well understood by the healthcare community as they should be.

So I’ve been reading a lot of probiotic clinical trials, and sharing what I’m learning here.

I hope Pharmacist Probiotics helps you find out if there is a type of probiotic that works for you!