Common Bacteria May Be One Cause of Type II Diabetes

Patrick M. Schlievert Ph.D Professor and Chair Department of Microbiology Carver College of Medicine Iowa City Iowa 52242 Interview with:
Patrick M. Schlievert Ph.D
Professor and Chair
Department of Microbiology
Carver College of Medicine
Iowa City Iowa 52242

Medical Research: What is the background for this study? Dr. Schlievert:

  1. As people become obese and enter pre-diabetes type II, there is a gut microbiome shift in bacteria from Bacteroidetes to Firmicutes. A dominant pathogenic Firmicute in humans is Staphylococcus aureus.
  2. As people become obese, their skin becomes wetter due to enhanced sweating upon exertion and the presence of more skin folds. These, plus mucous membranes have enhanced Staphylococcus aureus numbers, such that 100% of people become colonized and numbers of the bacterium rise to 1013 per person. This number of bacteria is like a cubic inch of margarine spread across the skin and mucous membranes.
  3. All pathogenic Staphylococcus aureus bacteria make and secrete a family of toxins called superantigens, including toxic shock syndrome toxin and staphylococcal enterotoxins. In high amounts (0.1 μg/human), these toxins can be lethal, causing toxic shock syndrome. At lower concentrations, the same superantigen toxins cause total body inflammation without lethality.
  4. In order to show that a microbes causes human disease, it is necessary to fulfill Koch’s postulates:
    1. Must associate human symptoms with a particular disease,
    2. Must isolate a potentially causative bacterium that is always present when the disease is present.
    3. Must produce the disease in an experimental animal.
    4. Must re-isolate the microbe from the experimental animal and re-cause the disease in another animal.

Medical Research: What are the main findings?

Dr. Schlievert: We have fulfilled Koch’s postulates, showing that Staphylococcus aureus and its superantigen toxins cause type II diabetes.

Medical Research: What should clinicians and patients take away from your report?

Dr. Schlievert:

  1. A common bacterium, Staphylococcus aureus, is one cause of type II diabetes.
  2. Staphylococcus aureus, including MRSA, can rise to very high numbers in and on obese persons, leading to elevated blood glucose and insulin resistance, the defining findings in type II diabetes.
  3. Some type II diabetic, and most type I diabetic patients, will have serious problems with the Staphylococcus aureus due to superantigen toxin production.
  4. Type II diabetic patients should change their lifestyles, such that if they are obese, they lose weight to reduce excess sweating in skin folds, thereby controlling the numbers of Staphylococcus aureus in and on their bodies.
  5. Who would have guessed that Staphylococcus aureus could do this? It reminds me of Helicobacter and ulcers…who would have thought?
  6. In serious cases, Physicians may try multiple antibiotics and IVIG to help control the diabetes.

Medical Research: What recommendations do you have for future research as a result of this study?

Dr. Schlievert:

  1. We are developing a novel antimicrobial that kills Staphylococcus aureus on contact. There is no chance of bacterial development of resistance to this antimicrobial. Similarly, the antimicrobial is anti-inflammatory. Type II diabetes has a significant chronic inflammation component caused by staphylococcal superantigen toxin. Both killing and prevention of inflammation can be obtained by this novel antimicrobial.
  2. Ultimately, vaccination is important. We have developed a vaccine that includes toxoids (non-active toxins) of superantigens. We expect this vaccine to be tested in humans within the next year or two. This vaccine could be used to immunize all humans against staphylococcal diseases.


Bao G. Vu, Christopher S. Stach, Katarina Kulhankova, Wilmara Salgado-Pabón, Aloysius J. Klingelhutz, Patrick M. Schlievert. Chronic Superantigen Exposure Induces Systemic Inflammation, Elevated Bloodstream Endotoxin, and Abnormal Glucose Tolerance in Rabbits: Possible Role in Diabetes. mBio, 2015; 6 (2): e02554-14 DOI: 10.1128/mBio.02554-14…pe-ii-diabetes/14699 (2015). Common Bacteria May Be One Cause of Type II Diabetes