CAMPYLOBACTER

Morphology: These are small, curved-spiral gram negative bacilli with polar flagella. Campylobacter jejuni appear in comma, S-shaped or "gull-wings/sea-gull" form.

Cultural characteristics: Growth is microaerophilic to anaerobic and they require an atmosphere of 10-20% CO₂ with a 5% or less of O₂. C.jejuni is fastidious (require blood for growth) and grows best at 42^oC. They are catalase and oxidase positive.

Significance: Many species of Campylobacter are animal pathogens. C.fetus is known to cause spontaneous abortions in cattle and sheep. Since campylobacter are harbored in reproductive and alimentary tracts of some animals, the transmission to human can be considered as zoonosis. Important human pathogens include C.jejuni and C.coli. They are important causative agent of food poisoning. Campylobacter associated diarrhea is more frequent in immunocompromised individuals.

Food poisoning: Transmission to humans occurs via a fecal-oral route, originating from farm animals, birds, dogs, and processed poultry, with chicken preparation comprising 50-70% of all campylobacter infections. The organism is transmitted to man in milk, meat products and contaminated water. Undercooked poultry and unpasteurized dairy are most often implicated as a source of C.jejuni. Campylobacter may be transmitted by sexual practices that promote anal-oral contamination. The incubation period of campylobacter enteritis is highly variable; it may range from 2 to11 days. As few as 500 organisms can cause enteritis. The organism is invasive but generally less so than Shigella. Campylobacter produces adenylate cyclase-activating toxins same as of E.coli LT and cholera. Patients present with abdominal pain and cramps, diarrhea, malaise, headache, and usually fever. Typically the diarrhoea is watery, but in severe cases bloody diarrhea may occur. Diarrhea may last 2-7 days and the organism may be shed in the patients stool for up to 2 months. 

Bacteremia is observed in a small minority of cases. The disease is usually self-limiting. Small numbers of cases may be followed by a severe neurological complication, Guillain-Barre syndrome. This is a syndrome of paralysis related to nerve demyelination. There appears to be a cross reactivity between antigens on Campylobacter and those on the nerve sheaths, which trigger the production of autoantibodies. 
C.jejuni can cause meningitis in infants. 

Laboratory diagnosis: The specimen collected is freshly passed feces. The feces may be inoculated in enrichment medium or on selective media such as Campy BAP or Skirrow's medium. Campy BAP is Brucella agar base with sheep blood, trimethoprim, vancomycin, cephalothin, amphotericin B, and polymyxin B. Skirrow's medium is 7% lysed horse blood agar with added vancomycin, polymyxin B, and trimethoprim. The plates are incubated in microaerophilic conditions at 42^oC for 2-5 days. 

Treatment: Antibiotics with significant therapeutic value are ciprofloxacin, gentamicin, azithromycin and erythromycin.