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Praca oryginalna
Original paper
Meat is indispensable for human nutrition as it
con-tains high biological value proteins, especially
exoge-nous amino acids. Nowadays, with new developments
in food technology (39), the variety of meat products
has increased. The growth of pathogenic bacteria in
meat and meat products is a potential source of risks
for human health. Consumers expect to purchase safe
meat but pathogens such as Salmonella spp., Listeria
monocytogenes and Escherichia coli O157 may cause
serious food safety problems for consumers. The poor
hygiene and sanitation conditions in the process of food
production encourage microbiological contamination,
survival and growth (21).
Salmonella spp., members of the Enterobacteriaceae
family, are Gram-negative, facultative anaerobes and
inhabit the intestinal tract of animals and constitute an
important pathogen for food industry and environment
(12). Beef and chicken are the foremost foods causing
salmonellosis (42). It was reported that Salmonella
infections cause approximately 1.4 million cases of
foodborne illness and more than 500 deaths per year
in the USA (6). In 2010, 99020 salmonellosis cases in
humans were reported in EU countries (15).
L. monocytogenes, which is a Gram positive, rod
shaped and psychrotrophic pathogen that is widely
distributed in the natural environment and in various
animal products, has been recognized as a causative
agent of listeriosis (9). L. monocytogenes can persist
and grow at low and high pH values, at low water
activity and at refrigeration temperatures (28).
Con-tamination with L. monocytogenes may occur during
slaughtering, processing and production processes of
meat and meat products. Immune-compromised adults,
pregnant women and neonates are included in high risk
groups for human listeriosis. In 2010, the number of
human listeriosis cases in EU countries was reported
as 1,601 (15). The illness has various symptoms such as:
fever, malaise, ataxia, endocarditis, endophthalmitis,
septic arthritis, osteomyelitis, peritonitis and in
pre-gnant humans, intrauterine infections, premature births
and abortions (13). Listeria was seldom detected
above the legal safety limit from ready-to-eat foods at
Prevalence of Salmonella spp.,
Listeria monocytogenes and Escherichia coli O157
in meat and meat products consumed in Istanbul*
)
ENVER BARIS BINGOL, EMEK DUMEN*, TOLGA KAHRAMAN,
MERYEM AKHAN*, GHASSAN ISSA**, OZER ERGUN
Department of Food Hygiene and Technology, Faculty of Veterinary Medicine, Istanbul University, Avcilar, 34320, Istanbul, Turkey
*Academic Hygiene KGaA, Training, Audit and Consulting Services, Kuþtepe Mahallesi, Tomurcuk Sokak, Ýzmen Sitesi, Sisli, 34387, Istanbul, Turkey
**Avrupa Vocational School, Culinary Programme, Kazlicesme, 34020, Istanbul, Turkey
Bingol E. B., Dumen E., Kahraman T., Akhan M., Issa G., Ergun O.
Prevalence of Salmonella spp., Listeria monocytogenes and Escherichia coli O157
in meat and meat products consumed in Istanbul
Summary
The present study was conducted to investigate the incidence of Salmonella spp., Listeria monocytogenes
and Escherichia coli O157 in 340 samples of meat and meat products (205 ground beef, 50 raw beef and 85
sausages) collected from producers and retailers in Istanbul. Salmonella spp. and Escherichia coli O157 analyses
were performed acoording to ISO standarts, while Listeria monocytogenes was confirmed according to FDA
methods. Salmonella spp. was detected in 1.18% samples. All samples were negative for L. monocytogenes
and E. coli O157. The results indicate that meat and meat products may be contaminated by pathogens which
can cause serious public health problems. Furthermore, the essential precautions should be undertaken to
ensure improving the quality of production technology.
Keywords: raw meat, meat product, Salmonella spp., Listeria monocytogenes, Escherichia coli O157
*) This work was supported by the Research Fund of the University of Istanbul,
Med. Weter. 2013, 69 (8)
489
retail, however, high mortality rate of disease (up to
20-30%) still threats the consumers health seriously
(13, 15).
E. coli O157:H7 or O157:nonmotile (E. coli O157)
is a neurotoxin producing enterohemorrhagic E. coli.
Typical illness may be life threatening, and
suscep-tible individuals show a range of symptoms including
haemorrhagic colitis and other complications, among
them haemolytic-uraemic syndrome and thrombotic
thrombocytopenic purpura (43). Cattle are natural
reservoirs of the pathogen and consumption of meat
of bovine origin is considered to be the main cause of
several outbreaks (38). A total of 4000 confirmed
verotoxigenic Escherichia coli (VTEC) infections were
reported and this number has been increasing since
2008 in the EU (15).
The present study was undertaken to determine the
presence of Salmonella spp., L. monocytogenes and
E. coli O157 in meat and meat products obtained from
retail markets and producers in Istanbul, Turkey.
Material and methods
Sample Collection. A total of 340 samples of meat and
meat products (205 ground beef, 50 raw beef and 85
sau-sages) were collected from producers and retailers in
Istan-bul. All samples were kept in sterile jars and immediately
transferred to the laboratory in cold boxes at 4°C.
Microbiological analysis. For the isolation of
Salmo-nella spp., pre-enrichment was performed by suspending
25 g of sample in 225 ml buffered peptone water (BPW
Oxoid CM0509) followed by incubation at 37°C for 16-20 h.
0.1 ml mixture was transferred to Rappaport-Vassiliadis
(RVS Oxoid CM0866) and 1.0 ml to Muller Kaufmann
Tetrathionate Broth (MKTTn Oxoid CM0343). MKTTn
at 37°C and RVS broth at 42°C were incubated for 24 h.
After incubation samples were streaked on Hectoen Enteric
Agar (Oxoid CM0419) and XLD Agar (Oxoid CM0469),
incubated for 24 h at 37°C. The typical colonies were
iden-tified by biochemical tests and confirmed with Salmonella
antiserum (O and H-Vi polyvalent antiserum) (30).
For detection of L. monocytogenes, 25 g of food
sam-ples were pummelled with 225 ml of Listeria Enrichment
Broth (Oxoid CM0862), contaning Listeria selective
sup-plement (Oxoid SR 141). Samples were homogenised in
a stomacher bag for 60 sec. and incubated at 32°C for 24 h.
A 0.1 ml portion of the enrichment broth was streaked on
to Chromogenic Listeria Agar (Oxoid CM1080)
supple-mented with Listeria Selective Supplement (Oxoid SR0227)
and Listeria Differential Supplement (Oxoid SR0228). After
incubation typical colonies were transferred to Tryptic
Soy-Yeast Extract Agar (Oxoid CM0131) and incubated for
24-48 h at 30°C. The typical colonies were verified by Grams
staining, catalase reaction, tumbling motility at 20-25°C,
Methyl Red-Vogues Proskauer (MR-VP) reactions, CAMP
test, nitrate reduction and fermantation of sugars (27).
For detection of E. coli O157, each sample was carried
out by combining 25 g of each sample with 225 ml of
modified Tryptone Soya Broth with (Oxoid CM0989) into
a stomacher bag, homogenized for at least 2 min and
incubated at 37°C for 24 h. Enriched culture was streaked
on to Sorbitol MacConkey Agar (Oxoid CM0813)
sup-plemented with Cefixime Tellurite Selective Supplement
(Oxoid SR172) which were incubated at 37°C for 18-24 h.
Following the incubation period, the colorless colonies were
tested by E. coli O157 latex kit (Oxoid DR0620) (29).
Results and discussion
Salmonella spp. was detected in 1.18% of the tested
meat and meat products (Tab. 1). The isolated
sero-vars were S. anatum in ground beef and S. reading and
S. meleagridis in sausage samples All samples were
negative for L. monocytogenes and E. coli O157.
According to Turkish Food Codex (47), the presence
of Salmonella spp. and E. coli O157 in 25 g of raw
beef and ground beef, the presence of Salmonella
spp. and L. monocytogenes in 25 g of sausages is not
acceptable.
The prevalence of Salmonella spp. in ground beef
samples tested in this study was lower in comparison
to those detected by Pietzsch&Kawerau (41) in
Germany (45.2%), Al Rajab et al. (2) in Iraq (18.0%),
El-Leithy&Rashad (16) in Egypt (15.0%),
Wolde-mariam et al. (50) in Ethiopia (12.1%) and Baskaya et
al. (4) in Turkey (11.1%). On the other hand, Gokalp
et al. (22) reported the prevalence rate of Salmonella
spp. was 2.0% in 48 ground beef samples. Other
studies stated the presence of Salmonella spp. in 1.4%,
2.0% and 2.08%, respectively (1, 31, 44). Our findings
showed similarity with the mentioned results, whereas,
Hinton et al. (26) and Krause et al. (32) did not find
any Salmonella spp. These differences may be
origi-nated from detection methods, sampling procedures
and the sanitation applications.
In the present study, Salmonella spp. was not
detec-ted in raw beef samples. This result was in accordance
to the findings reported by Cetinkaya et al. (6) and
Aydin et al. (3). In Northern Ireland 1.5% of 200 and
in Australia 0.22% of 1063 beef samples were tested
Tab. 1. Incidence of Salmonella spp. and Listeria spp. in various meat samples
t a e M f o e p y T NumberofSamples Salmonellaspp. Salmonellaserotypes Listeiraspp. Listeiraserotypes f e e B d n u o r G 205 2(0.98%) S.anatum 18(5.29%) L.innocua,L.seeilgeir t a e M f e e B w a R 50 negaitve negaitve 4(1.18%) L.seeilger,iL.welshimeir e g a s u a S 85 2(2.35%) S.reading,S.meleagirdis 3(0.88%) L.innocua,L.welshimeir s e l p m a S l a t o T f o r e b m u N 340 4(1.18%) 25(7.35%)
Med. Weter. 2013, 69 (8)
490
contaminated with Salmonella spp. (34, 48). They
explained that the prevalence of Salmonella spp. was
related with different hygiene applications and poor
manufacturing processes during slaughtering.
The present study demonstrated that Salmonella spp.
was isolated from 2.35% of sausages. Regarding the
contamination rate, our results were somewhat similar
to the study obtained by Oksuztepe et al. (40) in
Soudjouck (2.0%) and Duffy et al. (14) in cooked meat
(1.0%). In another study, no Salmonella spp. was
isolated (24). Contrary to this, the studies which had
higher results (61.5%, 26.0%, 24.4% and 7.0%) than
ours were reported by other authors (17, 36, 37, 45).
The reason for high contamination rate should be
due to the use of contaminated raw materials, lack of
proper heating and inadequate packaging as indicated
in EFSA report (15).
Ground beef, raw beef meat and sausages have been
examined in several countries for the presence of
L. monocytogenes. In Spain 34.9% of raw meat (49),
in Portugal 17.7% of raw meat (35), in Turkey 11.0%
of ground beef (8) and in Canada 15.63% of sausages
(19) were reported to be contaminated with L.
mono-cytogenes. In ours study, L. monocytogenes was not
detected. Similar results were reported by other
au-thors (5, 23, 33, 46). Differences between the findings
obtained from several studies can be related to the
pro-duction techniques, contamination from propro-duction
processes, preservation conditions and inadequate
per-sonal hygiene as stated in EFSA journal of 2012 (15).
It was also found that Listeria species were detected
in 25 (7.35%) samples, of which 18 (5.29%) were
L. innocua, 4 (1.18%) were L. seeligeri and 3 (0.88%)
were L. welshimeri.
According to the results from this study, no E. coli
O157 was isolated. Likewise, in other studies E. coli
O157 in sausages, ground beef and raw beef samples
(11, 18, 20) could not be detected. In contrast,
Cone-dera et al. (10) and Heuvelink et al. (25) demonstrated
that E. coli O157:H7 was isolated from 0.43% and
1.1% of ground beef respectively. Also, in Argentina
4.8% of the 83 fresh sausages and 3.3% of the 30 dry
sausages were contaminated with E. coli O157:H7 (7).
E. coli O157 is present sporadically at very low levels
together with very high levels of competitor organisms,
which is why it is difficult to detect (15).
Conclusion
In conclusion, the result of this study confirmed that
meat and meat products may be contaminated with
pathogens which can cause serious public health
pro-blems. Therefore, it is essential that applying good
hygienic practices (HACCP or GMP and GHP) and
developing standard procedures of production would
be benefical for controlling foodborne pathogens and
enhancing the safety of food.
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Corresponding author: Emek Dumen; e-mail address: emekdumen @yahoo.com
