Dichelobacter, Fusobacterium, and Bacteroides

Question 1

Interdigital dermatitis/footrot is caused by

Answer 1

Dichelobacter nodosus & fusobacterium necrophorum

Question 2

Morphology of D. Nodosus

Answer 2

Dumbbell shaped

Question 3

Morphology of F. Necrophorum

Answer 3

Fusiform w/ some beading

Question 4

Primary bacterium of footrot

Answer 4

Fusobacterium necrophorum

Question 5

Dichelobacter and fusobacterium have ______ interactions

Answer 5

Synergistic

Question 6

Clin signs of Footrot

Answer 6

• opportunistic pathogens
• causes lameness
• prev. By avoiding introd. Of animals from outside the herd

Question 7

Pathogenesis of Footrot

Answer 7

• isolation of the causative bacteria from environment & GIT doesn’t mean etiological assc. b/c normally found
• Inoculation poss. by fomites
• must have anaerobic conditions or concurrent infection w/ facultative bacteria

Question 8

Other 2 diseases Fusobacterium causes

Answer 8

• calf diptheria
• liver abcess (can only Dx @ slaughter)

Question 9

What diseases are Bacteroides assc. w/?

Answer 9

• abscesses
• diarrheal conditions
• PD (periodontal disease)
• bacterial pleuropneumonia in horses

Question 10

Dx for obligate anaerobes (Fusiform, dichlorobacter, bacterioides)

Answer 10

• don’t culture b/c expensive & takes too long & need experts
• most promising culture sites: have suppurative & necrotic processes
• samples should be in containers w/o O2
• DON’T REFRIGERATE SAMPLES

Question 11

Main 2 Dx for obligate anaerobes

Answer 11

Direct examination & isolation

Question 12

Most common Dx method for obligate anaerobes

Answer 12

Toxin ID

Question 13

Direct examination

Answer 13

• can give clues abt anaerobic presence
• shows unique morphologies
• look for: pale stained bacteria when safranin used (means gram -ve)
• infected material maya have foul smell

Question 14

Isolation

Answer 14

• not practical!!!!
• need continuous shielding from O2
• slow growth (>48 hrs)
• recommend blood-containing media