Week 16 Flashcards
Define bacteraemia
Spread of infection to distant organs
What does hematogenous spread mean?
The route of spread is blood.
Define septicaemia
Presence of bacteria/ toxins in the blood
What are some symptoms of sepsis?
Hi HR
hi respiration rate
Hi fever
Lo BP
Why does septic shock produce blood spots under the skin?
Blood coagulates under the skin as the vasculature breaks down
What is meningitis?
Inflammation of the meningeal (membranes lining the brain and spinal cord)
What is the most common pathogen type that causes meningitis? (viral, bacterial, fungal)
Virus
What do Kernig’s or Brudzinki’s signs involve?
Stretching hamstrings or hip flexors to see if neck is super stiff or if any pain is felt
What bacterial infection causes most of otitis media, sinusitis, lung infections, endocardium and meninges?
strept. pneumoniae
What gram is strept. pneumoniae?
Gram +ve
What kind of hemolytic is strept. pneumoniae?
alpha hemolytic
What is the most common vaccine for strept. pneumoniae?
Prevnar 13
What are the two main virulence factors of strept. pneumoniae?
a) pneumolysin damages lungs
b) H2O2 damages lungs and is produced by strept. pneumoniae
What is the basis for vaccines for strept. pneumoniae?
Capsular polysaccharide
What are the main bacterial cause of meningitis?
Strept. pneumoniae
Neisseria meningitidis
Is Neisseria meningitidis non capsulated or capsulated?
Capsulated
What gram is Neisseria meningitidis?
-ve
What’s the difference between endemic and epidemic?
endemic= infection maintained in population
epidemic= rate that exceeds ‘expected’
Why is the highest infection rate for Neisseria meningitidis at 6-7 months?
Passive maternal antibodies decline before the child’s immune system matures
What are the 5 main virulence factors for Neisseria meningitidis?
IgA protease
Pili- receptor specific attachment to nasopharynx
OMPs- closer interactions/ invasions
LPS
capsule=antiphagocytic
What causes the rash that doesn’t go away under glass?
meningococcal septicaemia
Where do extracellular bacterial pathogens reside?
Blood vessels
Lymphnodes
epithelial surface
Where do intracellular bacterial pathogens reside?
Cytoplasm
organelles
What are the two types of Intracellular bacterial pathogens?
Obligate-rely on host for primary metabolites
Faculative-can replicate in the absence of the host
Is Chlamydia an obligate or faculative pathogen?
Obligate
Is E.coli an obligate or faculative pathogen?
Faculative
Name some pros of intracellular living for a bacterial pathogen?
-evades immune response
-nutrients
-homeostasis
Name some cons of intracellular living for a bacterial pathogen?
-needs to enter host cell
-needs to escape the host to continue infection
What are the three methods to survive a macrophage?
1) ESCAPE= secrete exotoxins, disrupt phagosomal membrane
2) STAND+FIGHT=protective film and lo pH dependent replication
3)DODGE= prevent vacuole/ lysosome fusion
What pathogens use the ESCAPE method to survive macrophages?
Rickettsia
Shigella
What pathogens use the STAND+FIGHT method to survive macrophages?
Salmonella
MBT
Coxiella
What pathogens use the DODGE method to survive macrophages?
Chlamydia
How does shigella invade GI cells?
1) initial entry at Mcells
2)transfer to macrophages and epithelial
3)induces phagocytosis via disruption of actin cytoskeleton (membrane ruffles)
4) intracellular pathogens subvert normal cell function
What are the roles of M cells in the GI tract?
They sample the lumen of the GI to prep the lymphatic system
Via what adhesin does UPEC bind?
Dr adhesin bind to CEACAM
What are the 5 exit sttrategies for an intracellular bacterial pathogen?
1) Remodel actin cytoskeleton
2) Degrade the cell membrane
3) trigger apoptosis
4) trigger pyroptosis (same as apoptosis but with inflammation)
5) Extrusion
Is rickettsia obligate or faculative?
Obligate
What is interesting about the Rickettsia genome?
Small, degraded genome
Quite similar to human mitochondria
What causes rocky mountain fever?
R. rickettsia
What does rocky mountain fever look like?
Rash, swelling and fluid leakage (ticks)
What species of rickettsia is transmitted by body louse?
R. prowazeckii
Where does rickettsia replicate?
Endothelial cells of primary vasculature causing vasculitis
What serotype of chlamydia causes eye disease?
Trachoma
What are the symptoms of Trachoma?
Edge of eyelid is pulled inwards, eyelashes scrape and cause scarring of the cornea
What gram is chlamydia?
-ve
What is weird about chlamydia cell wall?
Very little peptidoglycan present, but it’s essential for cell replication so penicilin still works
Describe the chlamydia life style
1) elementary bodies enter through abrasions on mucosal surfaces
2)Endocytosis/actin remodelling
3) differentiation into reticulate body
4) multiplication of elementary bodies and release t o spread infection
