PHEW

Question 1

Isolation of Campylobacter is carried out on which kind of agar and under what conditions?

Answer 1

Blood-based agar (eg CCDA) under reduced oxygen tension

Question 2

Which agar is frequently used to identify enterobacteriacae and why?

Answer 2

MacConkey agar- Bile salts inhibit non-enterics

Question 3

Out of E.coli and salmonella, which ferments lactose to form pink colonies on agar gel? (colour change from yellow to pink)

Answer 3

E. coli

Question 4

What family of bacteria does salmonella fall into?

Answer 4

Enterobacteriacae

Question 5

Which antigens allow E.coli to attach to the urethra/bladder and cause urinary tract injections?

Answer 5

K antigens

Question 6

What are the clinical signs of E.coli?

Answer 6

Diarrhoea, septicaemia,

Question 7

How does E.coli attach?

Answer 7

Via pili and fimbria

Question 8

Which toxins cause entero-haemorrhagic E.coli, by damaging blood vessels?

Answer 8

Shiga-like toxins

Also act on kidneys causing haemolytic uremic syndrome

Question 9

Urinary tract infections are associated with which strains of E.coli?

Answer 9

Capsular strains

Question 10

Where is the main site of colonisation of E.coli?

Answer 10

Distal rectum

Question 11

How are humans infected with salmonella?

Answer 11

Via meat or eggs from infected animals or foodstuffs contaminated with faeces from infected animals
Person-to-person transmission in families

Question 12

How long do salmonella symptoms last?

Answer 12

4-7 days

Question 13

Human campylobacteriosis results in what side effect?

Answer 13

Painful diarrhoea which is often profuse but self-limiting

Question 14

Why is the broiler chicken the main source of campylobacter?

Answer 14

Core temperature of 41-42°C suits the thermophilic bug
Low oxygen tension in gut suits microaerophiles
High levels of growth supported in caeca (up to 1010 CFU per g)
High levels of shedding in faecal and caecal droppings coupled with coprophagic behaviour lead to rapid spread through houses
Campy persists well in the caeca and birds can be infected by a succession of different strains
Feed withdrawal and transport lead to stress and increased shedding
Automated plucking, evisceration and use of scald and wash tanks lead to frequent cross-contamination on lines
Rapidly growing modern broiler breeds have relatively poor immune systems and may be susceptible to an increasingly nasty bug