Friday, June 15, 2012

Human Microbiome- 100 Trillion Bacteria

100 Trillion bacteria. This is the microbial mass contained within the human body. Think of these bacteria as our symbiotic allies, important for homeostasis and part of our normal flora. The human microbiome can vary between individuals and can be dynamic in nature.

Source: NIH
Here is an article published in the New York Times on the human microbiome. The Human Microbiome Project website can be found here.

As an infectious diseases physician, I cannot overstate the importance of human microbial 'normalcy'. Disruption of the normal microbial ecology can result in infections such as C.difficile colitis and yeast infections. In some cases, restoration is achieved through microbial transplantation, as in fecal microbiota transplantsIn other cases, interventions such as invasive devices, immunosuppressants and cancer chemotherapeutic drugs can result in bacterial invasion by our resident microbes from the skin, gastrointestinal and genitourinary systems. 

This last point is relevant for those who advocate the complete eradication of hospital acquired infections. Quite simply, the state of science in infection prevention is not yet robust enough to prevent all infections. When we subject patients to surgeries, invasive devices, immunosuppressives and strong chemotherapeutic medications, resident bacteria are given the opportunity to translocate or invade. For more, I refer you to Michael Edmond's insightful commentary on healthcare without infection.

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