Anaerobic Bacteria

Question 1

Types of anaerobic bacteria

Answer 1

1. Obligate - harmed by presence of O2
2. Facultative - can grow w/o 02 - can use O2 if present
3. Microaerophiles - grow in low atmosphere of 02

Question 2

Why do anaerobic bacteria grow slowly?

Answer 2

Slow process which isn’t as efficient (sulphate production) - anaerobic respects uses electron transport chain but final acceptor isn’t oxygen

Question 3

Give example of where anaerobic bacteria may grow?

Answer 3

Sub-gingival plaque biofilm

Question 4

What the major anaerobic spp in humans

Answer 4

Clostridium spp - large gram +ve

Question 5

Virulence in clostridium spp

Answer 5

Produce endospores and exo-toxins

Question 6

What is cl. Perfringes

Answer 6

Capsulated non-motile gram +ve rod

Question 7

How detect cl. perfringes?

Answer 7

Nagles reaction - organism cultured on egg yolk media
One side contain anti-alpha toxin other side doesn’t not
Area turbidity form around side w/o toxic = uninhibited lecithinase activity

Question 8

What disease are caused cl. perfringes?

Answer 8

1. Gas gangrene - spore contamination of wounds –> oedema, gas formation, necrosis –> tx = surgery, ab
2. Food poisoning - incubate 10-12hrs - cause abdominal cramp and diarrhoea (vomit unusual)

Question 9

What disease caused cl. tetanus?

Answer 9

Acute spastic paralysis caused potent neuro-exotoxin - lockjaw (truisms) and rictus grin

Question 10

How does cl. tetanus cause disease?

Answer 10

Enter body through wound/ splinter - spores in environment.
Grow in wound and toxin released into body
Track along CNS

Question 11

How does tetanus toxin work?

Answer 11

A domain is active site, B domain has receptor binding

A = zinc endopeptidase which prevent release of inhibitor transmitter - no muscle relaxation

Question 12

Tx tetanus?

Answer 12

Anti-toxin + penicillin and metronidazole

Prevent - immunisation

Question 13

What is botulism?

Answer 13

Flaccid paralysis and neurological symptoms caused by ingestion of food w/ cl. botulism
Cause severe form of food poisoning

Question 14

What toxin is associated w/ botulism?

Answer 14

7 types A-G (A,B, E most common)

Botox

Question 15

What is c. difficile

Answer 15

Antibiotic associated diarrhoea - w/ broad spec ab inc. ampicillin and clindamycin

Question 16

Virulence C. difficile

Answer 16

Spore forming - resistant to heat and disinfection

Spore shed in faeces

Question 17

Complication of C. difficile

Answer 17

Pseudomembranous colitis - rupture –> sepsis

Question 18

Mechanism of c.difficile toxin?

Answer 18

Inactivate Rho - family GTPase cause neutrophil infiltration, disruption of tight junction and fluid accumulation

Question 19

Tx C. difficile?

Answer 19

Vancomycin or metronidazole - remove offending ab

Question 20

Examples of black pigmented anaerobes ?

Answer 20

1. Prevotella - gram -ve rod shape
2. Porphymonas - gram -ve rods (periodontal e.g p.gingivalis)
3. Fusobacteria - gram -ve (Associated ANUG)