Host-Microbe Relationships

Host-Microbe Relationships

1. Symbiotic vs. Non-symbiotic

   • Symbiotic: two organisms live together in close partnership
     • Mutualism
       • both members benefit
     • Commensalism
       • one benefits; other neither benefits nor is harmed
     • Parasitism
       • one benefits; other is harmed
   • Non-symbiotic: organisms are free living; relationship not required
     • Synergism
       • members cooperate to produce a result that none of them could do alone
     • Antagonism
       • actions of one organism affect the success or survival of others in the same community

2. Colonization, Inefection, Disease

   • Containment
     • an impurity
   • Colonization
     • the precense of bacteria on a body surface
   • Infection
     • pathogenic microorganism penetrate host defense
   • Disease
     • any deviation from health
     • infectious disease
       • disruption of tissues or organs caused by microbes

3. Acquiring Resident Biota

   • Benefits of normal biota
     • influence the development of organs
     • prevent the overgrowth of harmful microorganisms
   • endogenous infections
     • cause by biota already in the body

4. Progression of infection

   • Virulence
     • The relative severity of the disease caused by a particular microorganism
   • Virulence factor
     • any characteristic or structure of the microbe that contributes to toxin production
   • Attenuate
     • to reduce the virulence of a pathogenic bacterium or virus

5. Adhesion

   • process where microbes gain a more stable foothold on host tissues

6. Signs and Symptoms

   • Sign
     • objective evidence of disease noted by observer
   • Symptom
     • subjective evidence of disease noted by patient
   • Syndrome
     • a disease identified by a certain complex of signs and symptoms

7. Infections go unnoticed

   • Asymptomatic, subclinical, inapparent
     • host is infected but does not manifest the disease
     • patient experiences no symptoms