Medical Research: What is the background for this study? Dr. Schlievert:
- 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.
- 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.
- 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.
- In order to show that a microbes causes human disease, it is necessary to fulfill Koch’s postulates:
- Must associate human symptoms with a particular disease,
- Must isolate a potentially causative bacterium that is always present when the disease is present.
- Must produce the disease in an experimental animal.
- 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.