Campylobacter jejuni

• Widespread on farms - hyperendemic
• Carried as commensals in intestines of cattle, sheep, dogs, wild birds and especially chickens
• Farm animals regularly exposed via faecal-oral route; maternal antibody protects while active immunity develops
• Animals with little exposure are very susceptible, e.g. humans, pets
• Most chicken carcasses contaminated, leading to food poisoning and enterocolitis in people from uncooked meat
• Colonisation, attachment and invasion of colonic enterocytes; toxin production
• Necrosis of colonic absorptive epithelial cells, erosion of mucosa, crypt abscesses, inflammatory infiltrate of neutrophils into mucosa causes colitis
• Enteritis and diarrhoea in susceptible dogs; treatment with enrofloxacin
• Causes abortion in ewes
• Usually asymptomatic infections in chickens and turkeys, but occasional outbreaks of avian hepatitis occur with decreased egg production, loss of condition, haemorrhage and necrosis of liver; phase contrast microscopy demonstrates curved rods in bile; in-feed dihydrostreptomycin sulphate in outbreak
• Implicated in undifferentiated neonatal calf diarrhoea, a mixed viral enteritis in calves

• An important enteropathogen of man and a number of animal species.
• The largest cause of food-poisoning in the UK.
  • Is therefore a public health issue.
• Very widely distributed on the farm- carried in the intestinal tract of:
  • Cattle
  • Sheep
  • Dogs
  • Chickens
  • Wild birds
• Widespread distribution on the farm means that it is hyperendemic.
  • All animals are regularly exposed to it by the faecal oral route.
  • Passive (colostral) protection is helpful while active immunity develops.
• There is no regular exposure in the hygienic environment of the human or pet dog.
  • These animals are much more susceptible to infection.
• The intestinal contents of the broiler chicken may be spread around the abdominal cavity at slaughter.
  • Most poultry is moderately or heavily contaminated.
    • If frozen chicken is inadequately thawed, bacteria may remain viable in the abdominal cavity.
    • Bacteria may be ingested by humans handling the raw meat.

Pathogenesis

• Bacteria colonise the gut, attach to and invade the mucosa, and produce toxin.
• Causes colitis, characterised by:
  • Necrosis of absorptive epithelial cells
  • Erosion of the mucosa
  • Crypt abscesses
  • Infiltration of inflammatory cells into the mucosa.
    • Primarily neutrophils.
• Functional flagella are important as virulence factors.
  • Non-flagellate campylobacter do not colonise in vivo, and are less invasive in vitro.
• Diagnosed by laboratory diagnosis.