Microbiology L2 Flashcards
What are the three reservoirs where bacteria live until they can invade a host?
- Animal
- Environmental
- Human/Animal carriers
What is zoonosis?
Disease that naturally spread from animals to humans (zoonoses, plural)
What are human carriers?
People who have been exposed to, and continue to carry, the causative agent of a disease
What are the 3 routes of transmission into a host (contract transmission)?
- Contact
- Vehicle
- Vector-borne
What is contact transmission and the three types?
Spread from one host to another by direct, indirect contact, and droplet transmission
What is vehicle transmission and the three types?
Spread of pathogens by air, drinking water, and food
What is vector-borne transmission and the two types?
When insects transmit a disease by biological and mechanical methods
What is pathogenicity?
The ability of a microorganism to cause disease
What is virulence?
The severity or harmfulness of a disease
What are four virulence factors?
- Adherence
- Invasion
- Immune inhibitors
- Toxins
What are adherence factors?
Promote attachment to host cells, e.g. the use of fimbriae
What are invasion factors?
Help pathogen break down the hyaluronic acid, e.g. hyaluronidase
What are immune inhibitors?
Factors that help pathogens inhibit or invade the hosts’ immune system, e.g. producing factors that inhibit phagocytosis of macrophages
What are toxins?
Chemicals produced by pathogens that either harm tissue or trigger host immune responses that cause damage
What are the two types of toxins?
- Exotoxins
- Endotoxins
What are exotoxins?
Potent chemicals produced by bacteria and released into the environment.
- usually produced by Gram positive bacteria
- usually protein based
- secreted only while cell is alive
- sensitive to heat
- highly antigenic
- highly specific
- potent
- spread throughout body
What are endotoxins?
Chemicals produced by certain bacteria.
- Primarily produced by Gram negative bacteria
- Released when bacteria dies
- Stable at high temps
- Poorly antigenic
- Mostly composed of lipid
- Not specific
- Not potent
- Usually cause fever in host
- Local
Six factors on whether a disease will develop?
- Virulence
- # of microorganisms (dose)
- Host resistance
- Factors lowering resistance
- Natural immunity
- Microorganisms that work together
What is selective media?
Inhibits growth of some types of bacteria but allows the growth of others
What is differential media?
Contains an indicator that causes a colour change when certain types of bacteria are present
