lecture 9 - bacteria and fungi

Question 1

How do the pathogens get in?

Answer 1

Question 2

Meningitis

Answer 2

inflammation of meninges fibres

Question 3

causes of meningitis

Answer 3

Question 4

Neisseria meningitidis

Answer 4

Gram-negative diplococci
Polysaccharide capsule
Antigenic
Used for serotyping
Carried asymptomatically by 20% of the population
Colonises nasopharynx
Spread by droplets
Invasion poorly understood

Question 5

Symptoms of meningitis

Answer 5

Question 6

Virulence factors

Answer 6

• capsule
• IgA Protease
• Pili
• Endotoxin
• Outer membrane proteins

Question 7

Capsule

Answer 7

Polysaccharide capsule
Essential for survival in the bloodstream
Inhibits invasion and adhesion - regulated

Question 8

IgA Protease

Answer 8

Cleaves the hinge region in IgA1.
Creates immunologically inactive Fc and Fab fragments

Question 9

Pili

Answer 9

Type IV pili extend past the capsule
Attach cells to the host surfaces

Question 10

Endotoxin

Answer 10

LOS endotoxin (lipooligosaccharide) - similar to LPS but missing O-antigen polysaccharide
Released in outer membrane blebs
diffuse vascular damage largely attributed to the action of the LOS endotoxin

Question 11

Outer membrane proteins

Answer 11

Opa and Opc
Bind to host CEACAM receptor family, as well, ECM fibronectin and/or vitronectin
Other OMP inc. Por A and PorB, Rmp proteins

Question 12

Vaccination for different serotypes

Answer 12

Geographical variation in serotypes
In UK – B, W, Y and C predominant
A and W-135 are common elsewhere
Conjugate vaccine of capsule polysaccharides
Covers A, C, W, and Y
B serogroup
α(2-8)-linked sialic acid homopolymer
identical structure to human fetal neural cell-adhesion molecule (NCAM)
Instead use outer membrane vesicles

Question 13

Neisseria gonorrhoeae

Answer 13

Gonorrhoea – typically effects the genitals
Can get extragenital infection in pharynx and rectum
Untreated can cause disseminated infection
E.g. polyarthritis and meningitis
Antibiotic resistance is becoming more of a problem but is treatable

Question 14

Cryptococcus neoformans

Answer 14

Has tropism for CNS
Travel from lungs to the brain
Effects patients with depressed cell-mediated immunity
E.g. AIDS
Slow on-set
Days to weeks
Treat with combination of amphotericin B and flucytosine
Poor CSF penetration
Toxicity

Question 15

Borrelia burgdorferi

Answer 15

causes Lyme disease

Question 16

Lyme disease phases

Answer 16

Question 17

Lyme disease

Answer 17

Question 18

Neurological impacts of diseases

Answer 18

Question 19

Sphyilis

Answer 19

caused by Treponema pallidum
- treatable

Question 20

Sphyilis stages

Answer 20

Question 21

Sphyilis diagram

Answer 21

Question 22

Botox and tetanus

Answer 22

Question 23

The Clostridium bros:

Clostridium tetani
Clostridium botulinum

Answer 23

Gram-negative bacilli
Anaerobic (do not need oxygen to grow)
Form spores – to persist in harsh environments
C. tetani like a tennis racket
C. botulinum in the middle
Treat with antitoxin and prevent with toxoid vaccine
Not widely available for C. botulinum
Disease is mostly caused by the toxins
TeNT – locked paralysis
BoNT – floppy paralysis (BoTox)

Question 24

TeNT vs BoNT

Answer 24

Question 25

Staphylococcus aureus

Answer 25

Previously mentioned in context of MRSA Gram-positive cocci Normal part of flora but also able to cause a variety of infections Opportunistic pathogen Common cause of skin and soft tissue infections Impetigo, folliculitis, scolded skin syndrome

Question 26

S. aureus - how it works

Answer 26

Independent of any inflammatory response Mice knockouts used S. aureus localises proximal to sensory nerve endings Produces V8 protease Cleaves proteinase-activated receptor 1 (PAR1) Activating itch-associated Dorsal Root Ganglion neurons Similarly able to activate nociceptor neurons Inhibiting itch only allows the physiological role of inflammation while giving patients relief

Question 27

Zombie-Ant Fungus - Ophiocordyceps unilateralis

Answer 27