Fundamental Food Microbiology, Third Edition - Fuad Fathir

FOODBORNE INFECTIONS 377
Canada, the U.K., and Scotland. Isolation of Campylobacter spp. from a suspected
sample requires specific methods. After developing this method and incorporating
it to isolate suspected foodborne pathogens, Cam. jejuni has been confirmed as a
causative agent in many foodborne illnesses. Since it was first recognized as the
cause of an outbreak in 1979, Cam. jejuni has been implicated in 53 foodborne
outbreaks in the U.S. between 1979 and 1987, affecting 1547 individuals and resulting
in 2 deaths. The foods implicated most often in campylobacteriosis were raw
milk and improperly cooked chicken. Although several Campylobacter spp. have
been associated with foodborne campylobacteriosis, Cam. jejuni has been isolated
in most incidents; the discussion here is on Cam. jejuni. 1,2,26,27
B. Characteristics
Cam. jejuni is a Gram-negative, motile, nonsporulating, rod-shaped bacterium. The
cells are small, fragile, and spirally curved. The strains are microaerophilic and
catalase and oxidase positive. The strains require a microaerophilic environment of
ca. 5% oxygen, 8% CO 2, and 87% N 2 for growth. Growth temperature ranges
between 32 and 45�C, with optimum ca. 42�C. They grow better in amino acids
than in carbohydrates. They generally grow slowly and are not a good competitor
while growing with other bacteria. They do not generally grow well in many foods.
They are sensitive to many environmental parameters, including oxygen (in air),
NaCl (above 2.5%), low pH (below pH 5.0), temperature (below 30�C), heat (pasteurization),
and drying. However, they survive well under refrigeration and for
months in the frozen state. 28–30
C. Habitat
Cam. jejuni is an enteric organism. It has been isolated in high frequency from feces
of animals and birds. Human carriers were also found to shed the organisms in feces.
Fecal materials from poultry were found to contain �10 6 cells/g in some instances.
Water, sewage, vegetables, and foods of animal origin are easily contaminated with
Cam. jejuni excreted through feces. 29,30
D. Toxins
Cam. jejuni has a thermolabile enterotoxin that is responsible for enteric disease
symptoms. The toxin cross-reacts with cholera toxin, and the toxin production trait
is plasmid linked. In addition, the strains produce an invasive factor that enables the
cells to invade and establish in epithelial cells in both the small and large intestines
in humans. 29,30
E. Disease and Symptoms
The infective dose for campylobacteriosis is considerably low, only ca. 500 cells.
Following ingestion, symptoms of the disease occur in 2 to 5 d. Symptoms generally
last for 2 to 3 d, but can linger for 2 weeks or more. Persons with no visible symptoms
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