Campylobacter species

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Overview

  • Live on mucosa of intestinal and genital tract and can be commensals or pathogens
  • Enteric species cause disease in humans
  • Other species cause infertility and abortion in cattle and sheep
  • Excreted in faeces of birds, (C. jejuni and C. lari) as well as pigs contaminating water and food supplies
  • C. fetus restricted to bovine prepucial mucosa


Characteristics

  • Curved, Gram negative rods
  • Polar flagellum aids motility
  • Daughter cells remain joined giving gull-wing or spiral appearance
  • Microaerophilic
  • Sensitive to drying
  • Thermophilic species - C. jejuni, C. coli
  • Non-thermophilic species e.g. C. fetus
  • Grow on enriched selective media e.g. Skirrow agar in 1-10% carbon dioxide and 5-10% oxygen tension
  • C. jejuni requires increased temperatures for growth
  • Many grow on MacConkey
  • Oxidase positive, non-fermentative
  • C. fetus subspecies venerealis and subspecies fetus have small, round, smooth, translucent colonies
  • C. jejuni has small, flat, grey colonies with watery appearance
  • Smears stained with dilute carbol fuschin for 4 minutes


Pathogenesis and pathogenicity

  • C. fetus subspecies fetus and subspecies venerealis possess a microcapsule (S layer) which resists phagocytosis and serum-mediated destruction and enhances survival in the genital tract
  • Antigens of S layer undergoes antigenic shifts in C. fetus subspecies venerealis, allowing persistence in the host
  • C. jejuni attaches and invades host enterocytes and produces enterotoxin-like substances
  • Flagellae of C. jejuni required for colonisation


Campylobacter fetus subspecies venerealis

  • Venereal infection of cattle
  • Infertility in female cattle
  • Found in glandular crypts of prepuce of bull with no clinical signs - carriers
  • Causes catarrhal inflammation in female genital tract
  • Endometritis prevents implantation until infection gone and causes early embryonic death, occasionally sporadic abortion
  • May remain infertile for 3-5 months before immunity develops, which lasts 4-5 years
  • Effective immunity includes induction of IgA in the vagina and IgG in the uterus
  • Bacteria may persist in the vagina and be transmitted to bulls
  • Diagnosis:
    • Fluorescent antibody test on genital discharges from bull/cow
    • Vaginal mucus agglutination test
    • ELISA to IgA antibodies in vaginal mucus after an abortion
    • PCR for detection in semen
  • Treatment: dihydrostreptomycin intrauterine for cows and systemically or topically for bulls
  • Vaccination: bacterin in oil adjuvant


Campylobacter fetus subspecies fetus

  • Sporadic abortion in cows and sheep
  • 10% of ovine abortions in the UK
  • Enteric organism of sheep, goats and cattle; faecal-oral transmission
  • Ingestion during last trimester of pregnancy causes a bacteraemia
  • Bacteria reach the uterus
  • Necrotic placentitis causes late abortion, still birth or weak lambs
  • Sporadic abortion in cattle
  • Aborted lambs may have round necrotic lesions on surface of liver
  • Aborting ewes source of infection for vulnerable animals
  • Up to 20% of flock may abort
  • Solid immunity developed
  • S layer immunodominant antigen
  • Diagnosis: hepatic lesions in lambs; presence of organisms in foetal abomasum; isolation and identification
  • Treatment/control: isolate aborting ewes; destroy placenta; move other ewes to clean pasture; vaccinate flock with bacterin during outbreak and prophylactically; chlortetracycline in feed in an outbreak


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