BLBS102-c44 BLBS102-Simpson March 21, 2012 14:34 Trim: 276mm X 219mm Printer Name: Yet to Come
44 Emerging Bacterial Food-Borne Pathogens and Methods of Detection 837of infection. Incubation times of 2–70 days after eating contam-
inated foods have been reported (Bortolussi 2008). Often, the
symptoms appear as a mild flu-like illness with slight fever, ab-
dominal cramps, and diarrhea. In healthy individuals, the symp-
toms usually subside with no significant side effects; patients
do, however, continue to shed the pathogen for considerable pe-
riods postinfection (Marth 1988). In susceptible individuals, the
initial listeriosis infection results in enteric symptoms with nau-
sea, vomiting, abdominal cramps, diarrhea, fever, and headache
being common. However, as the pathogen leaves the gut result-
ing in a systemic infection the symptoms change. In pregnant
women, infection of the fetus can occurin uteroresulting in abor-
tion or preterm delivery; alternatively, the infant may present
with symptoms of infection early (<7 days) or late (>7 days)
postdelivery. Infants diagnosed early (<7 days) are most likely
infected transplacentally, while those presenting with listeriosis
late (>7 days) do not appear linked to maternal infection but the
sources of infection are poorly understood (Bortolussi 2008).
Symptoms of infection in infants and the immunocompromised
include bacteremia, meningitis, encephalitis, and endocarditis.
Fatality rates in unborn and newborn infants may be as high as
50% and has an average case fatality rate of 20–30% in others
(Swaminathan and Gerner-Smidt 2007).
The infective dose to cause illness is considered to be
100–1000 cells; however, individuals that are compromised may
be susceptible to lower doses (Ray 2004c). Cooked and ready-
to-eat meat and poultry have been implicated as sources of the
pathogen, and the growth of the organism has been demonstrated
in refrigerated ready-to-eat meats and raw foods that may pose
as significant health risk for consumers (Lianou and Sofos 2007,
Swaminathan and Gerner-Smidt 2007).
The pathogenesis ofListeriais associated with the invasive
ability of the organism, its ability to evade the host defenses, the
ability to produce a hemolysin called listeriolysin O, and cross
the blood–brain barrier (Drevets and Bronze 2008). Despite our
knowledge ofListeriaand methods of its control, the pathogen
is still a significant risk to populations within the community
and education of consumers is essential to ensure the safety of
certain foods such as ready-to-eat meats and vegetables.ArcobacterThe genusArcobacterwas first introduced in 1991, when it was
identified as a distinct member of the family Campylobacter-
aceae (Vandamme et al. 1991, Vandamme and De Ley 1991).
There are currently six recognized members of the genus includ-
ingA. butzleri,Arcobacter cryaerophilus,Arcobacter skirrowii,
Arcobacter cibarius,Arcobacter halophilus, andArcobacter ni-
trofigilis(McClung et al. 1983, Houf et al. 2005). Although the
organism still remains relatively unknown,Arcobacteris rec-
ognized as an opportunistic pathogen and a commensal and an
emerging pathogen of human concern (Ho et al. 2006, Snelling
et al. 2006).
To date, studies have foundArcobacteris a contaminant of
water and foods of animal origin.Arcobacterhave been asso-
ciated with abortion in bovine, porcine, and ovine (Vandamme
et al. 1992a,b, On et al. 2002). On et al. (2002) suggests thatsome strains ofArcobacterplay a primary role in abortions
and reproductive disorders, while other stains may be oppor-
tunistic pathogens. Regardless,Arcobacterhas frequently been
associated with production animals and it appears that animals
can be healthy carriers (Hume et al. 2001). The organism has
been recovered from the feces of healthy animals including
poultry (Houf et al. 2005), cattle (Wesley et al. 2000, Kabeya
et al. 2003), pigs (Hume et al. 2001, Kabeya et al. 2003, Van
Driessche et al. 2004), lamb, and equines (Van Driessche et al.
2003). Poultry appear to be a significant source of the pathogen
with contamination occurring on carcass surfaces. Gude et al.
(2005) reported thatA. butzleriwas commonly found in poul-
try abattoirs with carcasses being contaminated during process-
ing. Atabay and Corry (1997) suggest that although there is a
high prevalence ofArcobacteron poultry, the organism does
not appear to be common in the gut of poultry suggesting that
contamination of carcasses may arise from other sources during
processing.
Arcobacteris a gram-negative organism capable of growth un-
der aerobic and anaerobic conditions; however, optimal growth
appears to occur under microaerobic conditions (3–10% O 2 ).
The organism is considered a potential zoonotic agent due to
its association with animals and the detection ofArcobacterin
foods of animal origin including chicken, pork, lamb, and beef
(Kabeya et al. 2004, Rivas et al. 2004, Morita et al. 2004, Lehner
et al. 2005).Arcobacterhave also been associated with water
including a water reservoir, river or surface water, ground wa-
ter, and sewage (Diergaardt Jacob et al. 1993, Rice et al. 1999,
Stampi et al. 1999, Moreno et al. 2003, Morita et al. 2004,
Diergaardt et al. 2004).
Although the organism is relatively unknown, it has been
recognized as a potential agent of enteric disease and extrain-
testinal invasive diseases such as septicemia and bacteremia (Ho
et al. 2006). In animals,Arcobacterhas been recognized as
a cause of diarrhea and hemorrhagic colitis (Vandamme et al.
1992a, Vandamme 2000). While in humans,Arcobacterwas
reported as the fourth most commonCampylobacter-like or-
ganism isolated from the stool of human patients in Belgium
and France (Vandenberg et al. 2004, Prouzet-Mauleon et al.
2006).
As mentioned above,Arcobacteris capable of growth under
aerobic and anaerobic atmospheres with optimum growth under
microaerobic conditions. The organism has a growth range of
15–37◦C with an optimum of 30◦C. This strict growth range
may explain the lack of detection of the organism in the gut
of poultry where the temperature is about 42◦C.Arcobacter
does also possess distinct abilities for growth at 15◦C, which
differentiates it fromCampylobacterspp.Arcobactercan grow
at a pH range of 5 and 8.5 with an optimum of 6 and 8 at 30◦C
(Hilton et al. 2001). Storage at 4◦C resulted in a 4 log reduction
over 21 days and freezing at− 21 ◦C resulted in a 2 log loss after
24 hours but remained constant thereafter.
Evidence suggests that there is an association betweenAr-
cobacterand human disease with food playing a role; however,
the factors associated withArcobacterand human disease are
not well understood and warrant further investigation of the epi-
demiology, pathogenesis of and nature of this organism.