Meat consumption increases worldwide in parallel with increasing challenges in meat hygiene and safety (Iyer et al., 2013). Infections of foodborne Salmonella spp. are important worldwide and are recognized as the second most common foodborne pathogen in the European Union (Bonardi, 2017). Types of Salmonella spp, isolated from meat products are resistant to many drugs and can cause very serious problems (Soltan Dallal et al., 2014). As a result of Salmonella spp. infection in the United States, 26.500 hospitalizations, 1.35 million cases and 420 deaths occur each year (Bjelland et al., 2020). Most of which seen in children aged up to 4, 155.000 deaths occur per year due to Salmonellosis caused by the most common serotypes S. enteritidis and S. typhimurium (Evangelopoulou et al., 2015). In our study, Salmonella spp. and S. aureus, ranked first among foodborne pathogens that threaten public health reportedly by World Health Organization (WHO) and the European Union, have shown to have positive correlation and to stimulate their development (Table 2).
Table 2
Bilateral correlation relations of samples in terms of analyzed parameters
Parameter | Correlation coefficient / Significance | Coliform | E. coli | S. aureus | Salmonella spp. | S. typhimurium | S. enteritidis | L. monocytogenes |
Coliform | r | 1.000 | .276 | .421 | .665 | .534 | .221 | .900 |
p | -------- | .000 | .000 | .003 | .005 | .000 | .000 |
E. coli | r | .220 | 1.000 | .444 | .556 | .788 | .712 | .840 |
p | .000 | -------- | .000 | .004 | .000 | .000 | .000 |
S. aureus | r | .754 | .49* | 1.000 | .543 | .800 | .887 | .291 |
p | .003 | .004 | -------- | .000 | .000 | .000 | .000 |
Salmonella spp. | r | .702 | .675 | .231 | 1.000 | .398 | .506 | .312 |
p | .005 | .000 | .000 | -------- | .000 | .000 | .000 |
S. typhimurium | r | .342 | .754 | .300 | .802 | 1.000 | .876 | .521 |
p | .005 | .010 | .000 | .020 | -------- | .000 | .000 |
S. enteritidis | r | .901 | .860 | .521 | .106 | .286 | 1.000 | .547 |
p | .000 | .021 | .012 | .003 | .001 | -------- | .004 |
L. monocytogenes | r | .723 | .055 | .467 | .602 | .866 | .377 | 1.000 |
p | .003 | .000 | .019 | .032 | .040 | .005 | -------- |
Bilateral correlation relations are demonstrated by Kendall's tau-b relationship analysis method. |
Since E. coli EHEC O157:H7 and T. gondii were not detected in any example, these parameters are excluded from evaluation. |
Numerals written with bold characters are statistically significant (p<0.005). |
The significance is that it stimulates the reproduction of the other for each binary parameter. That is, the presence of one of both parameters, which is significant, positively affects the reproduction of the other. |
In a study conducted by Zarei et al. (2013); in a total of 210 samples, each 500 g collected from retail outlets and popular supermarkets, the prevalence of Salmonella spp. was 7.1% in lamb (n=70), 4.3% in beef (n=70) and 2.8% in buffalo meat (n=70) (Zarei et al., 2013). In our study, prevalence of Salmonella spp. was 12% in minced meat obtained from restaurants/kebab houses/vendors, 4% in beef, 3% in mutton, and 2% in sheep brain obtained from butcher’s. Another study examined 60 meat samples obtained from hypermarkets (n=20), groceries (n=20) and butchers (n=20); the prevalence of Salmonella spp. was determined to be 45% in butchers, 25% in grocery stores and 5% in hypermarkets (Iyer et al., 2013). In a study conducted on 189 beef and 190 chickens, 45% of chicken samples and 20.2% of beef samples were found to be positive for Salmonella spp., and one of the most isolated serotypes in unpackaged products was S. enteritidis (Soltan Dallal et al., 2014). In another study conducted by Ristori et al. (2017) on 552 chilled meat products (138 hot dogs, 138 raw pork sausage, 138 raw minced meat, 138 raw chicken legs); in terms of Salmonella spp., 62.5% of the positive specimens were pork sausage and 37.5% of chicken legs. In addition, while in terms of Salmonella spp., 12.5% of the positive samples belonged to S. enteritidis and 28.1% belonged to S. typhimurium serotypes, in our study 4% of minced meat was positive for S. typhimurium and S. enteritidis, but mutton, beef and sheep brains were not positive in terms of mentioned serotypes (Ristori et al., 2017). In another study, Salmonella spp. was isolated in 38.06% of 155 poultry offal (Sanda Abdelkader et al., 2019). In a study of pig offal products, 21.8% of 370 samples were positive for Salmonella spp.; intestinal (20%), brain (21%), liver, heart (73%) and kidney (87%) samples were determined to be suitable for human consumption (Erickson et al., 2019). This shows that, with the appropriate use of adequate heat treatment of meat products, cooling, freezing processes, application of correct cooking and packaging techniques, outbreaks of these pathogens can be prevented as a result of the absence of cross-contamination of meat products with other products ready for consumption.
In our study, it was determined that the highest risk food in terms of all microbiological parameters was minced meat. The foods that are risky after minced meat for Coliform, E. coli EHEC 0157:H7, S. aureus and Salmonella spp. were beef, mutton and sheep brain, respectively. Salmonella spp. and E. coli are the main factors that can lead to infections with food poisoning. In a study conducted by Zafar et al. (2016); 30 pieces of minced beef, mutton and chicken meat were examined and the highest microbiological load in terms of Salmonella spp. was seen in minced beef (6.57-7.39), followed by chicken and mutton, respectively (Zafar et al., 2016). In another study, 8.34% of the meat collected from the market, 11.86% of mutton, 12.59% of pork and 13.53% of chicken meat were contaminated with Salmonella spp., in which the greatest risk was found to be in chicken meat (Tadesse and Gebremedhin, 2015). In the study conducted by Martínez-Chávez et al. (2015); risk factor for Salmonella spp. pathogen was 71% (±11) for minced meat, 39% (±10) for beef pieces and 18% (±6) for beef carcasses, whereas for E. coli it was found to be 100% for minced meat, 97% (±27) for beef carcasses and 84% (±8) for beef pieces. This is due to the fact that during the processing of raw meat in butchers, the microbial load on meat is transferred to minced meat and to beef pieces, and also caused by the sources of cross-contamination such as chopping board-knives, other equipment and staff (Martínez-Chávez et al., 2015). In the study conducted by Zerabruk et al. (2019), it was reported that there were risks in terms of E. coli (43.75%), S. aureus (37.5%) and Salmonella spp.; and also, meat was not separated from offal, sold openly for 5 hours, and butchers were not hygienic (Zerabruk et al., 2019). In another study, the riskiest nutrients for Salmonella spp. were lungs (lights) (7.5%) and mombar (2.5%); for S. enteritidis (5%) and S. typhimurium (2.5%) was lungs (Abd-El-Malek and El-Khateib, 2017). In the study conducted by Ras et al. (2019), the risk ranking for S. aureus was found for cattle-sheep kidney (30%), buffalo-camel kidney (20%); buffalo liver (30%), cattle-camel liver (% 20) and sheep liver (0%). For E. coli, the buffalo and the camel kidney and liver had the same risk (20%). Risk was not present in beef liver-kidney and sheep liver (0%) (Ras, 2019). Both our study and other studies show that in order to prevent the high-risk level observed in terms of mentioned parameters, it is necessary to follow the necessary rules, good production practices, sanitation standard operating procedures and food safety systems during cutting and processing of animals due to contamination of offal.
Although there is not enough data, undercooked and raw meat is considered to be the most important cause of T. gondii infections that are effective in muscle and nerve tissues in humans (Sroka et al., 2019). This parasite leads to clinical manifestations such as encephalitis, hepatitis, pneumonia, myalgia and myocarditis in immunosuppressed individuals (Ducrocq et al., 2021). In the study of raw and smoked sausage, ham, dried bacon and minced meat, 5.4% of the samples were positive for T. gondii. 45.1% of the positive samples were sausages, 27.4% were smoked meat products, 19.4% were minced meat and 8% were ham (Sroka et al., 2019). In a study conducted in Turkey, T. gondii was present in 20% of the ovine muscle, 19% of fermented sausage, 6% of the bovine muscle, 4.17% of the ovine brain and 2% of the bovine brain. With regard to this, it can be said that the risk of toxoplasmosis is high in uncooked/commercial meat and products (Ergin et al., 2009). In our study, on the contrary, no nutrient was positive for T. gondii. Based on these findings, it can be said that further study is needed to determine risk factors in T. gondii infections (Hussain et al., 2017).
In a study on the offal of the heart, liver, lungs, abdomen, small intestine and large intestine, the most common pathogens found in pork were Salmonella spp (23.8%), S. aureus (12.7%) and Clostridium perfringens (C. perfringens) (11.1%); and in cattle were Salmonella spp. and C. perfringens (7.1%) (Im et al., 2016). In our study, the risk ranking for sheep's brain was S. aureus (12%), coliform (8%), E. coli-Salmonella spp. (2%). Both studies were similar to the aspect of S. aureus risk. In another study, the risk factors for chicken liver were Salmonella spp. (24%), E. coli (20%), S. typhimurium (8%) and S. enteritidis (4%); and for gizzard were Salmonella spp. (36%), E. coli (28%), S. enteritidis (12%) and S. typhimurium (8%) (Hassanin et al., 2017). According to current studies, it can be said that Salmonella spp., in particular, is an important risk factor for offal. In the study conducted by Wai et al. (2020), chicken gizzard, liver and heart had similar risk for L. monocytogenes and Listeria spp. (Wai et al., 2020).
L. monocytogenes is a major pathogen known worldwide as the causative agent of listeriosis and contaminates with food. This pathogen is a bacterium that causes meningoencephalitis, cerebral abscesses, cerebritis, bacteremia, meningitis and sepsis, especially in immunosuppressed individuals and pregnant women, and has a high mortality rate (20 -30%) (Montero et al., 2015). In a study conducted by Bouymajane et al. (2021) in Morocco, 520 food samples were examined. It was found that 15 (2.9%) of the analyzed samples were contaminated with L. monocytogenes. It was observed in 5.7% of raw minced meat and raw sausage, while was found in 1.9% of raw beef, poultry and raw fish samples. Additionally, it was observed that all strains detected carried the actA gene (Bouymajane et al., 2021). In another study, the prevalence of L. monocytogenes in consumption-ready products was examined and 783 delicatessen products were analyzed. The positive ratio of the products sold with vacuum packaging was 2.7%, while it was reported to be 8.5% in delicatessen meat products packaged in the store (Garrido et al., 2009). Braga et al. (2017) in their study examined 3175 food samples from food factories and retail outlets and 11.2% of them were observed to have been contaminated with L. monocytogenes. In our study, 13% of the analyzed samples (sheep: 7%, beef: 5%) were contaminated with L. monocytogenes. The results of similar studies conducted in China (22%) (Chen et al., 2017) and Chile (25%) (Montero et al., 2015) were significantly higher than the results observed in our study. It has been reported that one of the causes of this may be the type of food analyzed (Braga et al., 2017).
S. aureus causes diseases from mild skin infections and food poisoning to more complicated cases of necrotizing pneumonia, endocarditis, osteomyelitis and toxic shock syndrome. However, it can gain resistance to many antibiotics, including methicillin and vancomycin, and therefore is listed as one of the 'priority pathogens' that threaten public health by the WHO (Shrivastava et al., 2018). In a study conducted in Czech Republic, 23 (35.4%) of 65 raw meat samples (poultry, beef, pork and rabbit) collected from retail outlets were found positive for S. aureus (MRSA) (Tegegne et al., 2021). In the study by Hanson et al. (2011), the overall prevalence of S. aureus was 16.4% (27/165) in commercially available meat samples. S. aureus was most commonly found in turkey (7/36, 19.4%), pork (10/55 samples, 18.2%) and chicken (8/45 samples, 17.8%). Beef meat has been reported to have a much lower prevalence (2/29 samples, 6.9%). In another study, a total of 145 meat samples from Danish supermarkets were examined. S. aureus was detected in 69% of meat samples. MRSA was detected in 19 meat samples (13%) and MRSA prevalence was reported as 4% in chicken, 52% in turkey and 15% in pork (Tang et al., 2017). In our study, 50% of the samples analyzed (mutton: 17%, beef: 21%, sheep brain: 12%) were contaminated with S. aureus. In this regard, it can be stated that results obtained in our study are lower than the ones in the study conducted in Denmark (Hanson et al., 2011), whereas higher than the ones in the Czech Republic (Tegegne et al., 2021).
In a study, 375 chicken and offal samples were examined and it was determined that 5 samples were contaminated with E. coli. E. coli O157:H7 was not found in the analyzed samples (Guran et al., 2017). In a study conducted in Morocco, samples of beef (n=52) and lamb (n=52) and veal offal (n=52) were randomly collected from butchers, supermarkets and slaughterhouses. It was reported in the study that half of the samples (n=26) were collected during the cold season and the other half (n=26) in the warm season. Coliform bacteria were determined as 2.5±1.2 cfu/g−1, 2.8±1.0 cfu/g−1 and 2.3±1.1 cfu/g−1 for beef, lamb and veal offal, respectively. Of all samples analyzed, 59 (37.8%) were positive for E. coli, of which 13 (25%) were beef, 23 (44.2%) lamb and 23 (44.2%) were reported as veal offal. However, it was reported that the average number of coliforms in meat samples collected from butchers and supermarkets is significantly higher than the samples taken from slaughterhouses. This is associated with the possibility that hygienic conditions in which the product is processed, ambient temperature and storage after butchering may be inappropriate or insufficient (Cohen et al., 2006). A study by Jaja et al. (2018) collected 400 samples from 2 official slaughterhouses and 112 swab samples from 5 unregistered animal slaughter points. Swabs were made before and after washing the carcasses. The total number of coliform bacteria in slaughterhouses varies between 5.0-6.3 kob/cm2 before washing and 4.6-6.3 kob/cm2 after washing. To ensure that coliform bacteria, and especially E. coli, the most prominent hygiene indicator, is not a threat to public health and access to reliable food, it is clear that it is necessary to provdie the hygiene conditions of production, equipment and personnel.
Our study found that 22% of mutton meat, 25% of beef and 8% of sheep brain samples were contaminated with coliform bacteria. In E. coli analysis, the results obtained were as follows: 11% of mutton, 16% of beef and 2% of sheep's brain were contaminated with E. coli. As in the study of Guran et al. (2017), there was no E. coli O157:H7 in any sample. As highlighted in other studies, these findings obtained in our study suggest that personnel, equipment, and operational hygiene and critical control points within the enterprise should be provided.