Microbial ecology comes of age and joins the general ecology community
- School of Dentistry, University of Southern California, 925 West 34th Street, Los Angeles, CA 90089
The article by Boles et al. (1) in a recent issue of PNAS is profoundly important because it addresses a major change in the etiology of human bacterial diseases that has passed unnoticed during the last half of the past century. Acute diseases caused by mobile cells of specialized pathogens have largely disappeared because we have identified the pathogens and countered with vaccines and antibiotics. Diphtheria, typhoid fever, and posttraumatic gangrene have ceased to threaten us. However, these acute epidemic diseases have been largely replaced (2) by environmental organisms that gain a foothold in the human body, especially in compromised organs (like the lung in cystic fibrosis), and initiate the invidious twin processes of inflammation and chronic disease. The new microbial enemies are common and ubiquitous in nature, they live in protected biofilms where they resist antibiotics and host defenses, and they can mount small or large acute attacks on the host that may eventually succeed when his or her defenses are depleted.
The “Insurance Hypothesis” in Biofilms in Bacterial Disease
In their article, Boles et al. (1) relate modern biofilm diseases to the basic ecological principles that govern all forms of life on the planet, and they wisely invoke the insurance hypothesis that is well established in general ecology (3). Microbial ecology has not yet embraced either the concepts or the methods developed to study the ecology of higher plants and animals, so microbial ecologists stand to learn every bit as much from this masterful review as do the medical ecologists to whom it may seem to be directed. When a human is attacked by bacteria, our elaborate innate and acquired defense mechanisms swing into action, and the attackers soon become defenders, as cytokines immobilize phagocytes, and defensins and antibodies flood the area and kill the invaders. If the threatening agents are homogeneous, and if they operate …
