Survival of Campylobacter spp. in chicken rinse
samples during different storage times in constant
or fluctuating temperatures and in different rinse
fluids
Mint Marea Throns
0352942
Begeleider: Len Lipman
Survival of Campylobacter spp. in chicken rinse samples during different storage times in constant or
fluctuating temperatures and in different rinse fluids
Index
Index ................................................................................................... 1
Summary ............................................................................................. 3
Introduction .......................................................................................... 4
Materials and method ............................................................................. 7
Results ................................................................................................. 9
Conclusion and discussion ..................................................................... 11
Literature ........................................................................................... 12
2
Survival of Campylobacter spp. in chicken rinse samples during different storage times in constant or
fluctuating temperatures and in different rinse fluids
Summary
It is estimated that there are approximately 9 million cases of campylobacteriosis
in Europe each year. Per year in the Netherlands it was estimated that there are
on average 81,300 cases of this infection. Campylobacter jejuni and
Campylobacter coli are the most common strains causing campylobacteriosis in
humans. Usually the infection causes gastroenteritis which is self-limiting, but
complications can be severe.
The fact that up to 45% of the chicken meat in the supermarket exceeds the
infectious dose limit of 500 cells, makes it interesting to try to decrease the
contamination in slaughterhouses. To check if measurements to lower the
prevalence of Campylobacter spp. on meat are effective, samples of the chicken
meat must be taken. Moreover, when slaughterhouses are not in the direct
neighborhood of the laboratory, there will be time between sample taking and
analysis and storage conditions might influence the survival of the bacterium. In
this experiment the effect of the storage of rinse samples of chicken legs for 24
hours at constant 4˚C or in abused temperatures (2,5 hours at room temperature
and 21,5 hours at 4˚C) on the survival of Campylobacter jejuni and the effect of
different rinse fluids (buffered peptone water, peptone saline and saline) has
been checked.
The decrease in mean concentration was most pronounced in the rinse fluid BPW
(buffered peptone water) and in the abused temperature group. The decrease
was 0,30 CFU/ml in the inoculated rinse and 1,04 CFU/ml in the inoculate. It has
to be taken in account that these numbers are the result of limited data and
statistics are not reliable. Therefore more research is necessary.
3
Survival of Campylobacter spp. in chicken rinse samples during different storage times in constant or
fluctuating temperatures and in different rinse fluids
Introduction
Characteristics of Campylobacter spp.
Campylobacter spp. are Gram negative bacteria, that comprises of 23 species.
The bacteria have a spiral, S-shaped form or a coccoid form and they cannot
produce spores. The bacterium has polar flagella, so it is motile. Thermophilic
species (C. jejuni, C. coli, C. lari, C. upsaliensis and C. helveticus) grow under
high temperatures, preferably between 37 °C and 42 °C and in microaerobic
conditions (increased CO2 and less oxygen). Below 30 °C there is no growth
(EFSA,2011, ISO 2006, Quinn 2005).
Outside a warmblooded host (which can be all animals and humans),
Campylobacter spp. cannot multiply because of the absence of microaerobic
conditions and the warm atmosphere. Once outside a host the bacterium is
sensitive to several physical conditions like low water activity, drying, UVradiation and also heat (EFSA 2011, ISO 2006, Quinn 2005). But if the conditions
in the environment are favourable, Campylobacter spp. can survive up to three
months, for example in slurries or dirty water. (Nicholson 2005)
Campylobacter spp. can grow on and in quite a lot of media. ISO standards
(ISO/TS 10272-2, 2006) describe the isolation method as follows: enrichment in
Bolton broth, incubated at microaerobic atmosphere at 37 °C for 4-6 hours and
after that at 41,5 °C for 44 h ± 4 h. After that, or directly if the nature of the
sample allows to do so, plate it on mCCDA (modified charcoal cefoperazone
deoxycholate agar) and incubation at 41,5 °C for 44 h ± 4 h. (ISO 2006). When
plated on mCCDA plates Campylobacter spp. typically appear as a grayish
metallic colony with a tendency to spread. See figure 1.
Figure 1. Two pictures of Campylobacter jejuni colonies on mCCDA plates
Campylobacteriosis
In Europe alone approximately 9 million cases of campylobacteriosis occur each
year. In the Netherlands it was estimated that on average 81,300 cases per year
of campylobacteriosis occur (EFSA, 2011). Of all the cases in general, 20-30%
may be attributed to the handling, preparation and consumption of chicken meat.
Another 50-80% may be caused by the chicken reservoir as a whole.
(EFSA,2011) This means transmission of the infection with Campylobacter spp.
via the environment or by direct contact with chickens. Eggs are not seen as a
pathway for infection. The oviduct of the hen can be infected with the bacterium
but the prevalence in the egg itself is very low or non-existent. (Callicot 2005)
An infection with Campylobacter is usually associated with acute enteritis, which
can result in bloody diarrhea, fever and abdominal pain that can last up to 7
4
Survival of Campylobacter spp. in chicken rinse samples during different storage times in constant or
fluctuating temperatures and in different rinse fluids
days. Infections are usually self limiting, but if complications occur, they can be
severe. Complications can be:

Bacteraemia


Guillain- Barré syndrome, this is a demyelinating disorder which causes
acute neuromuscular paralysis, ± 20% are left with a disability, ±5% dies
(Altekruse 1999)
Reactive/septic arthritis

Inflammatory bowel disease

Irritable bowel syndrome
Death caused by the infection alone is rare, it will occur in YOPI’s (Young, Old,
Pregnant and Immunodeficient).
The main strains that are causing the human campylobacteriosis are C. jejuni and
C. coli. In the Netherlands about 10 % of the gastroenteritis cases reported, are
caused by Campylobacter spp., of which 90% is caused by Campylobacter jejuni
and 8% by Campylobacter coli. (De Wit 2001)
The infectious dose of Campylobacter spp. can be as low as 500 cells, but 15% to
45% of the batches of chicken meat for consumption tested, exceed these
numbers (Bhaduri 2004, Solow 2003, El-shibiny 2009, EFSA 2011). Therefore it is
interesting where in the primary production or in the slaughtering process
interventions can be made to reduce the contamination.
Measurements against contamination
When reducing the numbers of Campylobacter spp. in the primary production, the
most impact on the public health risk will be seen. If the concentration of
Campylobacter spp. in the intestines of livestock is reduced by 3 log10-units will
this reduce the public health risk by 90%. Not only the risk of infection decreases
when handling chickens at the farms and in the slaughterhouse, but it will also
help to reduce the risk of contamination of the environment and the carcass
during slaughtering. (EFSA 2011) Moreover, measurements like chemical or
physical decontamination after slaughtering might not be effective enough (e.g.
chlorine) or causes changes to the meat (freezing/heating) and this effect is
unwanted and should be kept to a minimum. (EFSA, 2011)
Measurements that can be taken to lower the prevalence in the primary
production are (EFSA 2011, Hermans 2011):




Biosecurity measurements like fly screens, keeping other animals (rodents
and other livestock in particular) away from the flock, hygiene barriers for
personnel, this measurement alone would provide a 50-90% public health
risk reduction of Campylobacter spp.
Providing good drinking water
Reduction of slaughter age, because flocks usually become positive after 4
weeks of age, this measurement would provide up to 50% public health
risk reduction
Discontinued thinning, thinning includes a lot of personnel and equipment
in the stables and so there is more chance on contamination. If the whole
flock is slaughtered at the same day the first part of the flock would (when
there was thinning), the slaughter age in total is reduced and this method
would provide up to 25% risk reduction
5
Survival of Campylobacter spp. in chicken rinse samples during different storage times in constant or
fluctuating temperatures and in different rinse fluids
A few other options are being tested like:
 Bacteriocins, proteinaceous toxins produced by bacteria, until now they
are effective in in vitro experiments
 Bacteriophages, also an effective measurement, but if the receptor for the
phage changes, the phage must change as well, otherwise the bacterium
will be resistant
 Vaccination, but until now no vaccine gave complete protection
 Feed and water additives, these additive would work through the
competitive exclusion concept. This means that a specific or non-specific
bacterial flora is given so Campylobacter spp. cannot grow. The nonspecific flora has worked best so far. Another option are adding short
chain fatty acids and a combination of other substances that work against
colonization
 Selective breeding, the chicken genome is known now, so the gene
involved with colonization can be traced
These kind of interventions will cost a lot of money or require very strict hygiene
protocols.
The EFSA report 2011 concludes that a reduction of only 1 log10-unit of
Campylobacter spp. on the chicken carcass will reduce the public health risk by
50-90%. A reduction of 2 log10-units in the concentration on the carcass would
result in >90% public health risk reduction. Rosenquist et al 2003 also estimated
that a 2 log10 concentration decrease on the carcass would cause a 30-fold
reduction in the incidence of human campylobacteriosis. Furthermore
interventions at the slaughterhouse will be easier to implement.
A few measurements that can be made in the slaughterhouse/processing plant:




Prevention of spoilage of intestinal contents, e.g. equipment used for
evisceration should be better adapted to the natural variation of carcass
sizes
Scheduled slaughter, the carcasses of flocks that have been identified
positive for Campylobacter spp. should receive special treatment like
freezing or heat treatment
Logistic slaughter, positive flocks should be slaughtered after the negative
flocks to avoid cross contamination
Decontamination of the carcasses by physical or chemical treatments
To test the hygiene protocols in slaughterhouses, samples from the chicken
carcasses/meat should be taken to determine the number of bacteria, in this case
Campylobacter spp.. Not always are slaughterhouses in the direct neighborhood
of the laboratory, and there is time between sample taking and analysis. The
storage conditions of the collected samples is important for the survival of
Campylobacter spp. E.g. Campylobacter spp. are bacteria that grow at higher
temperatures, ranging between 31-42°C (Hazeleger 1998, EFSA 2011) and they
are quickly less viable below those temperatures. During storage, refrigerators
can break down and during transport a constant temperature cannot always be
guaranteed. So therefore it is interesting to know what a dynamic temperature
during storage will do to the survival of Campylobacter spp. On top of that,
sampling often involves rinse fluids which by themselves also can influence the
survival of Campylobacter spp. in the samples.
6
Survival of Campylobacter spp. in chicken rinse samples during different storage times in constant or
fluctuating temperatures and in different rinse fluids
Aim of this research
The aim of this study is to find out whether the storage of rinse samples of
chicken legs for 24 hours at constant 4˚C or in abused temperatures (2,5 hours
at room temperature and 21,5 hours at 4˚C) will influence the survival of
Campylobacter jejuni. Moreover the effect of different rinse fluids (buffered
peptone water, peptone saline and saline) will be checked.
Materials and method
Diluents and dilution tubes
For this experiment the diluents (physiological) saline (0,85% NaCl), peptone
saline (PS, Biokar Diagnostics BK014HA) and buffered peptone water (BPW,
Biokar Trading BK018HA) were used. Bottles of 500 ml diluent and tubes with 9
ml diluents were used for making serial dilutions. Both bottles and the tubes were
sterilized for 15 minutes in 121°C.
For the enrichment, Preston broth was used. Bottles of Nutrient Broth No 2
(Oxoid CM 0067) were sterilized for 15 minutes in 121°C and after the bottle was
cooled down to about 50°C one vial Preston Campylobacter Selective Supplement
(SR0204E, Oxoid) and 1 vial of Campylobacter Growth Supplement (SR0232E,
Oxoid) was added. This Preston broth was stored in 4°C and it was used within
two weeks after preparation.
Inoculum preparation
An overnight culture was made from the Campylobacter jejuni reference strain
NCTC 12665 (ASG Lelystad) on a sheep blood agar plate (Biotrading). One colony
from the sheep blood agar plate was isolated and put in 5 ml of Brain Heart
Infusion (Oxoid CM 0225) in a cell culture flask. This flask was incubated at 37°C
for 24 hours on a shaker, continuously shaking at 150 rpm and in microaerobic
conditions. The microaerobic atmosphere was created by a placing the flask in a
jar in which one Campygen sachet (Oxoid) was added. The caps of the flasks
were loose, making sure the atmosphere in the flask was the same as in the jar.
After the 24 hours of incubation 1 ml of the overnight culture was used to make
serial ten-fold dilutions until 10-6 in the same diluents used as rinse fluid. This is
called the inoculums. The diluting of the overnight culture was done in duplo, so
one series could be stored in 4°C and one series could be used in the abused
temperature experiment, which means 2,5 hours at room temperature (about
18°C) followed by 21,5 hours storage at 4°C. An aliquot of 100µl of the dilution
10-3 until 10-6 was plated on a mCCDA plate (modified Cefaperazone Charcoal
Deoxycholate Agar, Biotrading). From the same dilutions 1 ml was put in 9 ml
rinse, see next paragraph.
Chicken rinse preparation and recovery of Campylobacter
Two chicken legs (drumstick and thigh, with skin) bought at a local supermarket
each week and with a weight of approximately 300/330 g per leg were used. For
making the rinse 275 ml of diluent (BPW, PS or saline) was added to the legs in a
sterile plastic bag, which is according to the ISO 6887-2 standards (a leg is about
1/5 to ¼ of a carcass and ISO 6887-2 advices 500 ml per whole carcass, Musa et
7
Survival of Campylobacter spp. in chicken rinse samples during different storage times in constant or
fluctuating temperatures and in different rinse fluids
al 2006, Liu and Niu 2008). The extra 25 ml was for compensating losses when
making the rinse and pouring it in a bottle.
The chicken legs and skin were massaged for one minute and then shaken
vigorously back and forth by hand for one minute. With a sterilized scissor a
corner of the bag was cut and the rinse was poured in a glass sterile bottle.
This rinse was divided in 12 aliquots of 9 ml in sterile plastic 15 ml tubes. These
aliquots were inoculated with 1 ml of the dilutions 10-3 until 10-6 from the
overnight culture. One series of 4 tubes with these inoculated rinses was stored in
4°C for 24 hours, another series of 4 tubes was placed on the table in the lab for
2,5 hours (= abused temperature group) and from the last series 100µl was
plated on mCCDA plates and incubated at 42°C for 48 hours.
From the chicken rinse itself serial ten-fold dilutions were made until 10-4 in the
same fluid as the rinse and 100µl of these dilutions were plated on mCCDA and
incubated at 42°C for 48 hours. After that 1 ml from these dilutions were put into
9 ml of Preston broth for enrichment and incubated at 37°C for 24 hours. This
was done to check whether the sample was positive for Campylobacter spp.
Another tube with 10 ml of the rinse was stored at 4°C for 24 hours and in
another tube 10 ml of the rinse was stored for 2,5 hours at room temperature
and after that in 4°C. This was used the next day to make new dilutions.
This protocol was repeated each week for five weeks in a row.
8
Survival of Campylobacter spp. in chicken rinse samples during different storage times in constant or
fluctuating temperatures and in different rinse fluids
Results
Campylobacter jejuni
Each week the concentration in CFU/ml and for Campylobacter jejuni in both the
inoculated rinse and the inoculate itself was calculated for all three diluents.
These concentrations were converted to log10 CFU/ml and then the mean log10
CFU/ml was calculated together with the standard deviation (St dev) for these
numbers.
The plates for the pure rinse gave very few reliable results, so no data is shown
for the pure rinse.
In table 1 the data of the inoculated rinse is displayed. The mean Campylobacter
spp. concentration on the first day (day 0) was 8,07±0,19 log10 CFU/ml in BPW,
8,04±0,25 log10 CFU/ml in PS and 7,16±0,53 log10 CFU/ml in saline.
After 24 hours of storage at 4 °C (day 1) the mean concentrations were
decreased to 7,97±0,06 log10 CFU/ml in BPW, 7,92±0,24 log10 CFU/ml in PS and
7,02±0,70 log10 CFU/ml in saline.
The mean concentrations after 24 hours of abused temperature were 7,77±0,27
log10 CFU/ml in BPW, 7,85±0,37 log10 CFU/ml in PS and 7,39±0,37 log10 CFU/ml
in saline. Also see graph 1.
The decrease in concentration in was 0,10 log10 CFU/ml after 24 hours in 4 C,
0,30 log10 CFU/ml in abused temperatures for the diluent BPW.
The concentration of Campylobacter jejuni decreased 0,12 log10 CFU/ml in
peptone saline after 24 hours in 4 C and 0,19 log10 CFU/ml in abused
temperatures.
In saline the concentration decreased 0,14 log10 CFU/ml after 24 hours in 4 C and
increased 0,23 log10 CFU/ml in abused temperatures.
Campylobacter log cfu per ml
Impact of storage temperature and type of diluents
on Campylobacter survival in INOCULATED RINSE during
24h storage
9
8
7
6
5
4
3
2
1
0
8.07
7.97
8,04
7.77
7.92
7.16
7.39
7.02
day 0
day 1 at 4C
7.83
day 1 abused temp.
Temperature conditions
Buffered peptone water
Peptone saline
Saline
Graph 1. Graphic overview of the concentrations of Campylobacter jejuni in the inoculated rinse
during storage.
9
Survival of Campylobacter spp. in chicken rinse samples during different storage times in constant or
fluctuating temperatures and in different rinse fluids
The mean concentrations Campylobacter jejuni in the inoculate (the overnight
culture) on the first day were 8,89±0,14 log10 CFU/ml in BPW, 9,01±0,18 log10
CFU/ml in PS and 8,75±0,01 log10 CFU/ml in saline.
After 24 hours of storage at 4 °C the mean concentrations were 8,90±0,26 log10
CFU/ml in BPW, 8,51±0,30 log10 CFU/ml in PS and 7,95±0,89 log10 CFU/ml in
saline.
The mean concentrations after storage in abused temperatures were 7,85±1,06
log10 CFU/ml in BPW, 8,44±0,21 log10 CFU/ml in PS and 8,89 log10 CFU/ml in
saline. Also see graph 2.
The difference in mean concentration was an increase of 0,01 log10 CFU/ml after
24 hours of storage at 4 °C and a decrease of1,04 log10 CFU/ml in abused
temperatures in the diluent BPW.
A decrease of 0,36 log10 CFU/ml was seen after 24 hours of storage at 4 °C and
0,43 log10 CFU/ml in abused temperatures in diluents PS.
In saline the mean concentration of Campylobacter jejuni decreased 0,80 log10
CFU/ml after 24 hours of storage at 4 °C and in abused temperatures 0,39 log10
CFU/ml.
Campylobacter log cfu per ml
Impact of storage temperature and type of diluents
on Campylobacter survival in INOCULATE during 24h
storage
10
9
8
7
6
5
4
3
2
1
0
8,89
8.87
day 0
8.75
8.90
8.51
7.95
day 1 at 4C
7.85
8.44
8.36
day 1 abused temp.
Temperature conditions
Buffered peptone water
Peptone saline
Saline
Graph 2. Graphic overview of the content of table 2
10
Survival of Campylobacter spp. in chicken rinse samples during different storage times in constant or
fluctuating temperatures and in different rinse fluids
Conclusion and discussion
The results show that in the inoculated rinse the greatest decrease in
concentration is found in the diluent BPW in the abused temperature group. The
decrease was 0,30 log10 CFU/ml. The data for the inoculated rinse was based on
mainly two or three reliable concentration measurements and therefore statistics
are not reliable. Also some of the concentrations after storage were higher than
on day 0. This might be explained by either false counting or no optimal growth
conditions for Campylobacter jejuni on the mCCDA plates of day 0.
For the inoculate the results show the biggest decrease in concentration in the
abused temperature group and in the diluent BPW. This decrease was 1,04 log10
CFU/ml. The data for the inoculate were based on four, three, two or even only
one reliable measurement and therefore statistics are not reliable as well. The
fact that there were so few reliable results are mainly explained by mixing up
dilutions and following the protocol wrong.
Although it seems that there is an impact on survival of Campylobacter jejuni of
temperature and diluents, the changes in concentrations are within one log 10 unit
and this could well be biological variation and it has to be taken in account that
these numbers are the result of limited data. So there is no conclusion possible at
this point, and further research is necessary to see if storage temperature and
diluents has an effect on the survival of Campylobacter jejuni.
11
Survival of Campylobacter spp. in chicken rinse samples during different storage times in constant or
fluctuating temperatures and in different rinse fluids
Literature
1. Anonymous, Preparation of test samples, initial suspension and decimal
dilution for microbiological examination. Part 2. Specific rules for the
preparation of the initial suspension and decimal dilutions of meat and
meat products. Microbiology of food and animal feeding stuffs, ISO/CD
6887-2, 2000, Association Française de Normalisation, Paris, France.
2. Anonymous, Horizontal method for the detection and enumeration of
Campylobacter spp. – Part 2: Colony count technique, Microbiology of food
and animal feeding stuffs, ISO/TS 10272-2, 2006.
3. Altekruse, S. F., Stern, N. J., Fields, P. I., Swerdlow, D. L.,
Campylobacter jejuni – An emerging foodborne pathogen, Emerging
Infectious Diseases, 1999, 5 (1), 28-35
4. Asselt, E. D. Van, Jacobs-Reitsema, W. F., Brakel, R. Van, Voet, H.
Van der, Fels-Klerx, H. J. Van der, Campylobacter prevalence in the
broiler supply chain in the Netherlands, Poultry Science Association, 87,
2008, 2166-2172
5. Bhaduri, S., Cottrell, B., Survival of cold-stressed Campylobacter jejuni
on ground chicken and chicken skin during frozen storage, Applied and
Environmental Microbiology, dec 2004, 70 (12), 7103-7109
6. Boysen, L., Vigre, H., Rosenquist, H., Seasonal influence on the
prevalence of thermotolerant Campylobacter in retail broiler meat in
Denmark, Food Microbiology, 28, 2011, 1028-1032
7. Callicot, K. A., Friðriksdóttir, V., Reiersen, J., Lowmann, R.,
Bisaillon, J. R., Gunnarsson, E., Berndtson, E., Hiett, K. L.,
Needleman, D. S., Stern, N. J., Lack of evidence for vertical
transmission of Campylobacter spp. in chickens, Applied and
Environmental Microbiology, 72 (9), 2006, 5794-5798
8. Chan, K. F., Tran, H. Le, Kanenaka, R. Y., Kathariou, S., Survival of
clinical and poultry-derived isolates of Campylobacter jejuni at a low
temperature (4 C), Applied and Environmental Microbiology, 67 (9), 2001,
4186-4191
9. EFSA Panel on Biological Hazards (BIOHAZ); Scientific Opinion on
Campylobacter in broiler meat production: control options and
performance objectives and/or targets at different stages of the food
chain. EFSA Journal, 9(4), 2011, 2105-2246
10. El-shibiny, A., Connerton, P., Connerton, I., Survival at refrigeration
and freezing temperatures of Campylobacter coli and Campylobacter jejuni
on chicken skin applied as axenic and mixed oculums, International journal
of food microbiology, 2009, 131, 197-202
11. Habib, I., Uyttendaele, M., Zutter, L. De, Evaluation of ISO
10272:2006 standard versus alternative enrichment and plating
combinations for enumeration and detection of Campylobacter in chicken
meat, Food Microbiology, 28, 2011, 1117-1123
12. Hazeleger, W. C., Wouters, J. A., Rombouts, F. M., Abee, T.,
Physiological activity of Campylobacter jejuni far below the minimal
growth temperature, Applied and Environmental Microbiology, 64 (10),
1998, 3917-3922
13. Hermans, D., Deun, K. Van, Messens, W., Martel, A., Immerseel, F.
Van, Haesebrouck, F., Rasschaert, G., Heyndrickx, M., Pasmans, F.,
Campylobacter control in poultry by current intervention measures
ineffective: Urgent need for intensified fundamental research, Veterinary
Microbiology, 2011, 152, 219-228
14. Josefsen, M. H., Löfström, C., Hansen, T. B., Christensen, L. S.,
Olsen, J. E., Hoorfar, J., Rapid Quantification of Viable Campylobacter
Bacteria on Chicken Carcasses, Using Real-Time PCR and Propidium
12
Survival of Campylobacter spp. in chicken rinse samples during different storage times in constant or
fluctuating temperatures and in different rinse fluids
Monoazide Treatment, as a Tool for Quantitative Risk Assessment, Applied
and Environmental Microbiology, Aug. 2010, 76 (15), 5097–5104
15. Liu, F., Niu, Z., Carcass quality of different meat- Typed chickens when
achieve a common physiological body weight, International Journal of
Poultry Science, 2008, 7 (4), 319-322
16. Musa, H. H., Chen, G. H., Cheng, J. H., Li, B. C., Mekki, D. M., Study
on carcass characteristics of chicken breeds raised under the intensive
condition, International Journal of Poultry Science, 2006, 5(6), 530-533
17. Nicholson, F. A., Groves, S. J., Chambers, B. J., Pathogen survival
during livestock manure storage and following land application,
Bioresource Technology, 96, 2005, 135-143
18. Rosenquist, H., Nielsen, N. L., Sommer, H. M., Norrung, B.,
Christensen, B. B., Quantitative risk assessment of human
campylobacteriosis associated with thermophilic Campylobacter species in
chickens, International Journal of Food Microbiology, 83, 87-103
19. Sampers, I., Habib, I., Zutter, L. De, Dumoulin, A., Uyttendaele, M.,
Survival of Campylobacter spp. in poultry meat preperations subjected to
freezing, refrigeration, minor salt concentration, and heat treatment,
International Journal of Food Microbiology, 137, 2010, 147-153
20. Solow, B. T., Cloak, O.M., Fratamico, P. M., Effect of temperature on
viability of Campylobacter jejuni and Campylobacter coli on raw chicken or
pork skin, Journal of Food Protection, 2003, 66 (11), 2023-2031
21. Wit, M. A. S. De, Koopmans, M. P. G., Kortbeek, L. M., Duynhoven,
Y. T. P. H. Van, Gastroenteritis in sentinal general practices, the
Netherlands, Emerging Infectious Diseases, 7 (1), 2001, 82-91
22. Quinn, P. J., Markey, B. K., Carter, M. E., Donnelly, W. J., Leonard,
F. C., Veterinary microbiology and microbial disease, Chapter 29
Campylobacter species, Blackwell publishing, 2005, p. 168-172
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