Oral and Poster Abstracts

using immuno-magnetic and pre-selective methods on samples from
a total of 542 cattle.
Results: 41 E. coli O157 (plus, 13 non-O157 VTEC) strains were
isolated (1% of cattle).
The O157 strains formed the following 3 pathogroups:
- EPEC (enteropathogenic E. coli) O157:H7 (22 strains) (eae + , stx - ),-
EHEC (enterohaemorrhagic E. coli) O157:H7 (11 strains), (eae + , stx + ),
- atypical O157 (8 strains), (eae - , stx - ), characterized by genes of the
cytotoxin CDT-V.The E. coli O157 strains frequently harboured long
polar fimbrial (lpf O113 and lpf R141) genes and pathogenicity island OI-
122 genes (including efa, sen and pagC). The fyuA, marker gene for
high pathogenicity island (HPI) was detected in some strains. Both
O157:H7 EPEC and EHEC possessed - type of intimin (eae) gene and
- type of translocated intimin receptor (tir) gene (characteristic for
human O157:H7 EHEC strains).
Pulsed field gel-electrophoresis (PFGE) revealed three clusters of
bovine O157:H7 strains:
- O157:H7 EPEC strains from large intestine of slaughtered cattle
(Cluster I),
- O157:H7 EHEC strains of the above slaughtered cattle (Cluster II),
- O157 atypical strains from raw milk samples of the dairy farm
(Cluster III)
This grouping was partly confirmed by multi locus sequence typing
(MLST) performed on five housekeeping genes.
Conclusions: it seems that O157:H7 strains are not infrequent in the
Hungarian cattle population. They represent EPEC and EHEC,
possessing virulence genes with zoonotic potential, although human
infection due to bovine EPEC has not been described yet. Our data
indicate that beside EHEC, the bovine O157:H7 EPEC and atypical
O157 E. coli strains deserve more attention in the future.
318 Comparison of Conventional Method and Microspheresbased
Assays for the Quantification of Kanamycin in Milk
L. Chen 1 , Y. Jin 2 , M. Zou 2 , X. Cui 1 , X. Hu 1 , B. Han 1
1
China agricultural University, College of Veterinary Medicine,
Beijing, China
2
Chinese Academy of Inspection and Quarantine, Institute of
Inspection, Beijing, China
Several techniques had been developed to quantify antibiotics in cow
milk; however, all of them possessed one or more significant
limitations and usually measured only one analyte at a time.
Competitive ELISA, which showed great correlation coefficient over
the range from 1ng/ml to 100ng/ml, was the most conventional assay
for quantifying low-molecular-weight compounds like antibiotic.
Immunochromatographic strip test, which could detect samples with
naked-eye, was more convenient but had a high detected limitation.
HPLC (high performance liquid chromatography) was more
reproducible, whose precision of within-day assay showed a 0.5 to
4.0% coefficient of variation (n=5) when the kanamycin concentration
ranged from 1x10 4
to 7x10 4 ng/ml. Although CE (capillary
electrophoresis) analysis could guarantee a good linearity in the
concentration range 400-5000 ng/ml with a detection limit of
100ng/ml, its intra-day and inter-day RSD (relative standard deviation)
were 3.4 and 11.2%, respectively, and its recoverability was as low as
approximately 60%. Currently, we used a novel multiplexed method
improved on the existing assay to measure kanamycin whose
concentration was from 0.1ng/ml to 3 ng/ml, and its intra-day and interday
RSD could reach to 3.4 and 4.1%, respectively. In this method,
antigens were covalently bound to carboxyl-modified microspheres,
which could be distinguished by their distinct proportions of red and
orange fluorescent dyes, and then were captured by monoclonal
antibody against kanamycin in milk samples. The main advantages of
such a method lay in its high efficiency, good biocompatibility,
excellent selectivity as well as ultra-low sample consumption, and it
showed a great potential for multiplex assay in the near future.
Key words: kanamycin, flow-cytometry, cow milk, ELISA, CE,
HPLC, multiplex assay
319 Quantitative Risk Assessment Model of Human Salmonellosis
linked to the Consumption of Camembert Cheese made from
Raw Milk
A. Fares, A. Dayhum, M. Sanaa, O. Cerf, Y. Millemann
Ecole Vétérinaire d'Alfort, Unité Epidémiologie et Analyse de Risque,
Maisons-Alfort, France
Salmonellae are one of the most important causes of foodborne
illness associated with raw dairy products. The assessment of the
real risk associated with the consumption of these products is needed
and the most appropriate method to achieve this goal is the risk
analysis process, which links pathogens in food to the public health
problem. The main aim of this work was the quantitative assessment
of the risk of human salmonellosis linked to the consumption of
Camembert cheese made from raw milk cheese. A data gap that is
routinely identified in risk assessment is the lack of quantitative data
on pathogens contaminated food; therefore, we developed a rapid,
sensitive and reliable method for the quantification of Salmonella in
artificially contaminated milk samples. The method combined the
principles of most-probable-number (MPN) method with a real-time
PCR assay. With this developed assay (MPN-real-time PCR) low
levels of Salmonella (1-5 CFU/mL) in milk could be enumerated
after 8 h of non-selective enrichment in buffered peptone water. This
developed quantification assay was applied to naturally
contaminated bulk tank milk samples collected from dairy farms
located in western France. Eight (2.6%) of 299 bulk tank milk
samples were found positive, with estimated MPN values ranging
from 3.7 to 79.2 MPN/mL of milk. In the assessment of potential
risks associated with Salmonella in raw milk and raw milk products
it was necessary to examine the ability of Salmonella to grow in
milk. Primary and secondary models, describing mathematically the
growth of two Salmonella strains (S. typhimurium and S. tontevideo)
in milk under constant temperatures during different incubation
periods, were developed. The primary logistic-with-delay model was
used to describe Salmonella strains growth as a function of time. The
specific growth rates of S. typhimurium and S. montevideo varied
according to serotype and temperature. Both the primary and
secondary models fitted growth data well with a high-pseudo R 2
(0.97-99). Finally, a quantitative risk assessment of human
salmonellosis linked to the consumption of Camembert cheese made
from raw milk is presented based on the results of the previously
mentioned objectives of this thesis. Different distributions were
assumed for parameters of the model and a Monte Carlo simulation
was used to model the process and to quantify the risk associated
with the consumption of 25 g serving of cheese.
Key words: salmonella, raw milk, risk analysis
320 The Seasonal Changes of Contamination Rate of Ovine Meats
to Salmonellae Bacteria Serotypes in Kermanshah
Dr. Bahiraie, Dr. Chale chale, Dr. Pouanmehr
Razi University,Faculty of Veterinary Medicine, Kermanshah, Iran
Objectives of study: The survey of contamination rate of ovine meats
(meats of sheep) in Kermanshah city. The comparisons of
contamination rate between two types of meat which delivered to
customers include absolute and grinded meat. The study and
comparison of differences of contamination rate during 4seasons of
year. The salmonellae serotyping in contaminated meats. The survey of
Serotypes Prevalence in each season.
Material and Methods: Bacteriological examination was carried out
on two sample groups of ovine meat (500 absolute meat and 500
grinded samples) .The samples were collected from meat markets of
city during four season of year (2005). Each was 50 grams of meats
which prepared to customers. The samples were were examined in
regarding to routine bacteriological examinations. Stereotyping by test
of Fast agglutination on slid and were confirmed by tube tests. Data
analysied in SPSS .Serotypes of salmonellae based on Kaffman-white
schema were identified.
Results: Salmonellae were isolated 31 out of 500 ovine absolute
meat samples (A.M.S) (%6.2) and 43 out of 500 ovine grinded meat
samples (G.M.S) (%8.6) totally during the year. The highest
contamination rate for A.M.S was with 13 cases in summer, 9
cases in fall, 7 cases in spring and 2 case in winter, and for G.M.S
samples was 17 cases in summer, 12 cases in fall, 10 cases in spring
and 4 case in winter, respectively. Stereotyping showed that: in two
groups of contaminated samples the S.typhimurium was the most
contaminator serotype The rates of contaminator serotypes for
absolute samples (A.B.S) were S. typhimurium (28.7 %) and then S.
enteriditis and for G.M.S were S. typhimurium (34.3 %) and then S.
enteriditis (22.4 %), respectively. S. paratyphi B, was found in
G.M.S 2 cases in fall and 1 case in summer. Distribution of the
serotypes of salmonellae in grinded samples G.M.S was more than
absolute meat samples.
Food Safety 269