Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 12/1/2001
Publication Date: N/A
Technical Abstract: Polymicrobial diseases represent the clinical and pathological mani- festations induced by the presence of multiple microorganisms. These are serious diseases whose etiologic agents are sometimes difficult to diagnose and difficult to treat. They are often called complex infections, complicated infections, dual infections, mixed infections, secondary infections, co-infections, synergistic infections, concurrent infections, or polymicrobial infections. These diseases in animals and humans are induced by polyviral infections, polybacterial infections, polymicrobial infections involving viruses and bacteria, polymicrobial infections involving fungi and parasites, and polymicrobial infections as a result of microbe-induced immunosuppression. There are five common underlying mechanisms of disease pathogenesis. First, physical, physiologic, or metabolic abnormalities and stress predispose the host to polymicrobial disease. Second, one organism induces changes in the mucosa that may favor the colonization of other organisms. Third, microorganisms or their products can trigger proinflammatory cytokines to increase the severity of disease, reactivate latent infections, or favor the colonization of other microorganisms. Fourth, organisms may share determinants among each other allowing them the ability to damage tissue. Finally, one organism can alter the immune system, which allows the colonization of the host by other microorganisms. Many areas of study in polymicrobial diseases are at their infancy, and it is our hope that the book Polymicrobial Diseases will stimulate interest and work in this evolving area.