Microorganisms and host

MICROORGANISM AND HOST
  • Saprophytes and parasites
  • Saprophytism – Living on dead or decaying organic matter.
  • Parasitism – Living on or within another living organism. In parasites there are different host parasite relationships.
    • Commenselism – The organism lives on the host without causing any disease.
    • Symbiosis – Mutally beneficial relationship
    • Opportunistic pathogen – The organism is generally harmless but can cause disease when it gains access to other sites or tissues.
    • Obligate pathogen – The organism always causes disease .
  • Infectivity – It is the capacity of the organism to become established in the tissues of the host. It is the ability to penetrate the tissues, to survive in the host defenses and to multiply and disseminate in the animal.
  • Pathogenicity – It is the capacity of the microbial species to produce disease.
  • Virulence – It is the measure of degree of pathogenicty. It refers to the capacity of of a microbial strain to produce disease
  • Depending on the susceptibilty or  resistance  of the host the microorganisms will produce disease.
Last modified: Sunday, 4 December 2011, 5:36 AM