Campylobacter

Campylobacter is a genus of gram negative, spiral shaped, microaerophilic and motile rods, which are oxidase positive.

Pathogenesis

Route of entry
Transmission is via feco-oral route. Domestic animals are major source of organisms e.g cattle, chicken, dogs. Food and water contained with animal faces is also a source.

Pathogenesis is not clear. These bacteria cause infections in the small and large intestine. They cause enterocolitis as well.
Enterotoxin is present, which acts like choleragen. Bacteremia may be produced as well. Invasion of cells often occurs.
Dose of 500-800 organisms is required for development of disease.

Virulence Factors

• Enterotoxin -lipopolysarrcharide
• Cytotoxins
• Flagella
• Campylobacter invasion antigens ( LIA proteins)
• Cytolethal distending toxin (CDT) (Arrests the cell in the G2-M transition phase of the cell cycle)

Predisposing Factors

• Undercooked food
• Unpasteurized milk
• Contaminated water
• Puppies with diarrhea
• Poor hygiene

More common in children

Clinical Symptoms

• Watery, foul smelling diarrhea which may convert into dysentery.
• Fever
• Severe abdominal pain

Immunological consequences:

• Guillain-barre syndrome (GDS), formation of antibodies against C. jejuni which cross-react with self-antigens on neurons (neuro muscular paralysis)
• Reactive arthritis
• Reiter’s syndrome

Laboratory Diagnosis

Specimen
•    Stool

Microscopy

Important characteristics include:

•    Gram- negative rods
•    Spiral, comma-S shaped
•    Flagellum is present
•    Motile

Culture

• Higher temperature is required for incubation -42 degrees
• Incubation period is 2-7 days
• Microaerophilic i.e. require 5% O2   instead of 20%  O2
• Capneophilic i.e. require 10% CO2
• Blood agar, form non-hemolytic, spreading colonies or droplet-like colonies

Improved Preston blood-free medium

• C.jejuni gives moist, grey colonies
• C.coli form creamy-grey colonies

Swarming growth may occur

Biochemical Tests

Catalase               Positive
Urease                  Negative
Oxidase                Positive
Resistant to         Nalidixic  acid
Hippurate            Hydrolysis positive is C.Jejuni
Hydrolysis negative is C.Coli

Serological Tests

• Latex agglutination test
• PCR

Treatment

• Erythromycin or Ciprofloxacin are effective against C. Jejuni
• Aminoglycosides are effective against C.intestinalis