Lecture 10 Flashcards
True pathogens
Organism causes infection in inividuals with normal host defences
Commensal
Organism normally found on parts of body that are exposed to or communicate with external environment
Opportunistic pathogens
Organism that can cause infection in individuals’ with abnormal host defences
Are most microbes pathogenic or non-pathogenic
Non-pathogenic
How many microbes are potentially pathogenic
Many
How many microbes are always pathogenic?
Very few
First Koch postulate
Pathogen must be present in every case of disease
Second Koch postulate
Pathogen isolated from diseased host and grown in pure culture
Third Koch postulate
Specific disease reproduced when pure culture of pathogen inoculated into healthy host
Fourth Koch postulate
Pathogen can be recovered from experimentally infected host
Issue with Koch Postulates
Viruses (2nd)
Host effects (3rd)
Polymicrobial infections
Infectious doses
What disease is 100% clinically apparent regarding infections
Rabies
What has low pathogenicity and high infectivity?
Common cold
What has high pathogenicity and low infectivity?
HIV
Examples of toxins
Diphtheria (toxoid immunisation), Cholera, Toxic shock
