Lecture 9: AofPathogen II, appendicitis Flashcards
What are the 3 factors that interact and determine the infection and outcome of infectious disease
Human host and their susceptibility, the pathogen and the environment
What factors impact hosts susceptibility to infection
- Risky behaviours
- immune deficiency illnesses
- chemotherapy that may be immunosupressive
- treatments that comprise the barrier of skin
What does virulence mean
The capacity to cause disease in hosts with intact defences. Varies between different types of pathogens
What is endogenous infection
Endogenous infection: arises from within the person’s own body from bacteria already on the person going to the wrong place
What is exogenous infection
Pathogens originating not from the person
- From human to human transmission,
- interacting with the environment: cholera and
- Zoonosis: transmitted from animals
What are virulence factors and what are the main 4 types
Genetic determinants that pathogen uses/ exploits to cause disease and avoid the immune system.
Adherence: to bond to cells
Invasion: capacity to damage cells eg. toxins
Immune evasion
Toxins
What is pyogenic infection
Acute inflammation which results in pus formation due to tissue invasion, multiplication and immune response in a sterile site
What is a granulomatous/ chronic infection
When the pathogen evades the innate immune system so there is an incomplete host response leading to formation of granuloma where activated macrophages fuse and surround the antigen
What are ways that bacteria toxin cause harm?
Intoxication: this is when toxins can cause changes in host physiology eg. cholera or it can cause tissue destruction eg. gangrene
How does pathogen damage host by immune mediation
This is where the antigens of pathogen mimic normal host cell antigens so that when the immune system makes antibodies against that particular pathogen, these mistakenly direct immune response against own tissues and this inflammation causes damage to the tissue eg. rheumatic fever
Can pathogens cause cancer?
Yes, Helicobacter Pylori causes stomach cancer; HPV can cause cervical cancer, Hep B
What are the basic steps of appenditic
the appendix in neonates helps to understand the good bacteria in the bowel
-Appendix
Hard faeces/ bowel contents and bacteria get trapped in the appendix. The bacteria compete for the resources in there.
Bacteria bind interact with cells lining the appendix, they release a toxin damaging those cells
Once hte cell hsa been cell releases cytokines to signal that they need help.
The cytokines lead to changes in surrounding structures. The neutrophiles fdo chemotaxis
Neutrophils engulf bacteria and kill them. toxic granules fuse with phagosome to for a lysosome and this is where the bacteria killed.
What are 4 steps that lead to unspecific abdominal pain because of the inflammation
- Faecolith blocks appendix, bacteria trapped there in the appendix bind to cells lining the appendix and release a toxin damaging those cells
- Damaged cell releases cytokines to signal that they need help
- The cytokines lead to changes in surrounding structures. Neutrophils leave blood vessels via chemotaxis
- Neutrophils engulf bacteria and kill them using their lysosome.
Describe the process of cholera infection in
- Vibrio cholera ingested from unsanitary water
- cholera divides in bowel and releases a toxin which inhibits GTPase, causing build up of cGMP
- build up causes Cl-pump to pump Cl- out of the cell
- This causes large loss of water chloride and sodium into the bowel lumen causing diarrhoea
Explain and describe the shift of pain during appendicitis
Initially inflammation in the appendix. Internal organs have imprecise sensory input. First perceived as Gut pain due to skin nerves and internal nerves entering the spinal cord around T10 (umbilicus). Later as inflammation spreads to the parietal peritoneum the pain shifts to the right illiac fossa due to more precise innervation.
