What are the three major factors that lead to opportunistic infections?
- 1. Failure of host's normal defenses (weak, unable to fight)
- 2. Microbe got into a wrong part of the body
- 3. Disturbance in Normal Microflora = super infection
How are diseases interact with population (refer to chart)
- 1. Endemic - low rate in population
- 2. Epidemic - higher than normal rate
- 3. Pandemic - disease high globally, spreading world wide.
Blood stream - terminology
- *bacteremia - bacteria in blood
- * toxemia - toxic in blood
- *viremia - Virus in blood.
- *Septicemia - bacteria reproducing in the blood, AKA (blood poisoning, systemic infection)
five steps of how microbe cause disease
- 1.Has to gain access to a host
- 2.Has to adhere to the host
- 3.Has to penetrate into a host
- 4.Has to evade the host immune response *with coaggulase*
- 5.Has to cause damage to the host
- a. Direct damage b. Accumulation of toxic waste products
What are the 3 portals of entry? which is most common?
Respiratory Route, Gastrointestinal Route, and Genitourinary Route --- Respiratory tract is the easiest
Reservior of Infection
Humans, other verterbrates, and non living items
disease spread from person to person
Virulence and how it's measured
- The degree of pathogenecity, ID --- dose to get 50% of population sick. LD --- toxins, dose required to kill 50% of population...
- *higher dose = less virulence!
4 enzymes that penetrate the immune system
- 1. Hyaluranidase - separate the tissue. spread of infection
- 2. Coagulase - forms blood clots, shield themselves from immune cells (HELPS EVADE FROM HOSTS IMMUNE SYS.)
- 3. Kinase - breaks down blood cloth; allow them to continue to invade
- 4. Collagenase - breaks down collagen, breaks conntective tissue to invade
3 types of exotoxins
- 1. A-B toxins (A= active, B = binding).
- 2. Membrane - disruption toxins. (kill WBC, RBC)
- 3. superantigens - type 1 toxin = intense immune response