Basics Flashcards
(18 cards)
Reasons for return of bacterial infections
- Antibiotic resistance
- Emerging and re-emerging diseases
- Bioterrorism
- Outbreaks of water and food borne diseases
- Hospital acquired (nosocomial) diseases
Definition of new-new diseases
Caused by previous unidentified microbes e.g Lyme disease
Definition of new-old diseases
Diseases that have been known for a long time but now we know the cause e.g Campylobacter and Helicobacter pylori
Definition of old-new diseases
Old disease with known causes once thought to be under control but have reappeared with new mutations e.g MRSA, Tb, E.coli, Influenza A
Definition of old-old diseases
Old diseases with old causes but recently ‘discovered’ with respect to recognition of importance e.g Chlamydia.
Definition of colonisation
Ability of a microbe to remain at a particular location and stay there.
Definition of infection
Successful colonisation and multiplication by a microbe capable of causing disease.
Definition of disease
A dynamic process involving a sufficient change in the normal function of an organism’s cells or tissues to cause symptoms.
Definition of pathogenicity
A microbe’s ability to cause disease.
Definition of virulence
The degree of pathology caused by a microbe.
Definition of pathogenesis
Mechanisms a microbe uses to cause the disease state.
Definition of virulence factors
Features that contribute to the ability of a microbe to colonise and cause disease.
Definition of pathogen
A microbe capable of causing disease.
Definition of True pathogens
Tend to produce disease readily in healthy hosts.
Definition of opportunistic pathogens
Only cause disease in a compromised host or when a particular microbe enters an unusual site in a host.
Name the 4 Koch’s postulates
- The microbe must be associated with symptoms of the disease and be present at the site of infection.
- The microbe must be isolated from disease lesions and grown as pure culture.
- Culture microbe should reproduce the disease when inoculated into a susceptible healthy host.
- The microbe must be re-isolated from the host in 3.
What are the modern techniques used to satisfy Koch’s postulates.
- PCR or immune-histochemistry can be used to detect the microbe.
- Antibiotic therapy can be used to eliminate the disease.
- Vaccination can be used to prevent disease.
- Hygiene, disinfection and health practices can be used to prevent exposure to the microbe.
What are the 6 molecular Koch’s postulates?
- Identify gene responsible for virulence determinant.
- The gene should only be found in strains of bacteria that cause disease and no in avirulent bacteria.
- The gene should be isolated by cloning.
- Distruption/knockout of the gene should reduce virulence.
- Introduction of the cloned gene into an avirulent strain should confer virulence.
- The gene should be expressed in the host during an infection.
