Non-sporing anaerobes

Question 1

Bacterial spp. + habitat + morphology

Answer 1

Peptostreptococcus - gram + 
Bacteroides - gram –
Prevotella - gram –
Fusobacterium - gram –
Dichelobacter - gram –

Environmental + commensals (alimentary/URT)

Question 2

Tx of non-sporing anaerobes

Answer 2

Penicillin
Metronidazole
» may not penetrate necrotic lesions

Drainage is important

Resistant to aminoglycosides/fluoroquinolones

Question 3

Sampling of non-sporing anaerobes

Answer 3

Anaerobic collection - syringe, large samples, smear immediately, don’t chill

Question 4

Disease manifestation of non-sporing anaerobes (2)

Answer 4

Opportunistic infections

Abscesses, body cavity effusions

Question 5

Bacteroides - disease manifestations (2)

Answer 5

B. fragilis
> abscesses
> Enterotoxaemia + diarrhoea

Question 6

Bacteroides - VFs (2)

Answer 6

Capsule polysaccharide > abscesses

Fragilysin (enterotoxin) > diarrhoea

Question 7

Necrobacillosis - agent + habitat

Answer 7

Fusobacterium necrophorum

Commensal of alimentary/UGT + in soil

Question 8

Necrobacillosis - associated diseases (5)

Answer 8

Bo liver/rumen abscesses (dt lactic acidosis)
Eq thrush
Bo calf diphtheria (dt faecal contam of milk)
Bo footrot
Ov foot abscess (heavy sheep)

Question 9

Necrobacillosis - agent + VFs (

Answer 9

Fusobacterium necrophorum

• Leukotoxin = anti-phagocytic
• Endotoxin

Question 10

Footrot in sheep - agent + habitat

Answer 10

Dichelobacter nodosus

- obligate parasite of hooves

Question 11

Ovine footrot - VFs (4)

Answer 11

Pili = colonisation + invasion
Proteases = horn digestion
Persist in underrun hoof for long periods
Strain variation

Question 12

Ovine footrot - host factors (2)

Answer 12

Breed susceptibility (Merino > british)
Agent survives in pockets of underrun hoof = source of infection

Question 13

Ovine footrot - Environmental factors (1)

Answer 13

Warm (> 10deg) + Wet (>500mm) conditions (spring)

Question 14

Ovine footrot - immunity (2)

Answer 14

No natural immunity

Pilus vax = Ab w short duration of immunity

Question 15

Ovine footrot - tx (4)

Answer 15

formalin/ZnSO4 footbaths = control spread
Foot paring
Penicillin/streptomycin (high dose)
keep sheep in dry environment

Question 16

Ovine footrot - pathogenesis

Answer 16

Warm + wet + faecal contam of hoof
> F. necrophorum colonises
> epidermal dmg = D. nodosus colonisation
> proteases digest horn = progressive invasion
> D. nodosus promotes F. necrophorum growth
> Local inflamm = epidermal lysis
> separation of horn + lameness