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