Meat and meat products are widely consumed in all countries and are rich in fat, protein, and many vitamins. In the last 50 years, following the doubling of the world's population, the consumption of meat products used in food has tripled [22].

In our country, the number of animals has reached more than 60 million, and animal products, especially meat, are used for food. We are ranked 10th in the world in terms of meat consumption, with 2.7 times more meat consumed than the world average [8].

The prevalence of S. aureus contamination in retail meat may depend on the number of samples studied, storage conditions, retail environment, and season. In our country, the meat sold in the markets may have a relatively high rate of contamination depending on the fact that it is sold at room temperature in all seasons, is sold in the open market, and is not transported by special vehicles from the meat preparation places.

According to our study, in the markets of Ulaanbaatar, S. aureus was identified in 35% of the retail meat samples. There have been reported many studies around the world. In these studies, S. aureus was determined between 16% and 54.4% of the raw beef samples [23,24,25,26,27]. For instance in a study in Iran by Zeinab Torki, S. aureus was found in 16% of raw beef for retail sale, [23] in a study by Bizuneh Tsehaynah, 54.5%, [24] and in a study by Qianting Ou, and 29.2% [25]. In a study conducted in Japan, it was also reported that 32.8% of the raw beef samples were contaminated by S.aureus [26]. Moreover, a study showed that 40% of item contaminated by S. aureus, 77.8% and 47.2% of which had resistance at tetracycline and clindamycin, respectively [28]. As compared with other countries, level of the beef contamination was similar to the item but antibiotic resistance was higher than that of another country. By result of study conducted in Turkey, 63.54% of the meat samples was contaminated with S. aureus and its antibiotic resistance was observed each antibiotic for example, oxacillin 12.5%, tetracycline 26.03%, chloramphenicol 23.96%, penicillin 78.2%, clindamycin 16.66%, and azithromycin 46.87% [27].

In Mongolia, 35% of the beef samples was contaminated by S. aureus and its antibiotic resistance including oxacillin 88.6%, tetracycline 22.8%, chloramphenicol 8.6%, penicillin 88.6%, clindamycin 37.1%, and azithromycin 34.3% was observed in our study. Hence, the contamination of retail beef samples is considered as public health hazard in Mongolia.

Since the prevalence of bacterial infections and inflammatory diseases among the population in our country has not decreased significantly, the use of antibiotics as drug treatments has been increasing year over year, the side effects of drugs have increased, and pathogenic bacteria have become resistant to antibiotics and more virulent [29].

In Mongolia, approximately 70% of all drugs are imported, and approximately 30% of the drugs used for treatment are antibacterial agents. Additionally, more than 700 drugs are registered in the state register for animal husbandry practice, but there are risks of serious damage to human health due to the haphazard and uncontrolled use of antibiotics, the use of drugs in food before it has been completely excreted, and infection with antibiotic-resistant bacteria [29]. Common food products such as contaminated raw meat and meat products are a common way by which antibiotic-resistant bacteria spread from animals to humans [30, 31]. In other words, the improper use of antibiotics in animals can lead to high levels of antibiotic resistance in S. aureus strains found in meat and meat products [1]. Antibiotic resistance is likely to increase, depending on factors such as the number of animals, the improper use of antibiotics, and use of animal feed containing antibiotics.

Uncontrolled large-scale use of antibiotics is the basis for the emergence of MDR strains, and MDR S. aureus is quite common in hospital environments and on farms [32]. In a study conducted in the Federal Democratic Republic of Nepal, all 6 strains of S. aureus detected in meat were identified as resistant to antibiotics, especially amoxicillin and tetracycline [33, 34]. Additionally, in a study conducted by Pesavento G. in 2007, the staphylococcal strains detected were resistant to beta-lactam antibiotics such as oxacillin and cefoxitin, and 30.95% of them were identified as MDR. According to the results of this study, most of the staphylococci were resistant to beta-lactam antibiotics such as oxacillin and ciprofloxacin. It was found that 43 (89.58%) out of 48 S. aureus strains were highly resistant to beta lactam antibiotics [35]. Forty percent (14/35) of the S. aureus strains detected in the raw meat samples included in our study were MDR, while 1 strain was resistant to all 9 antibiotics in all of the 7 groups selected.

The prevalence of MRSA in China and Russia, which border Mongolia, is 10–50%, which is very high, showing that this type of research is necessary in our country. In our study, 17.1% (6/35) of the S. aureus detected in raw beef were MRSA. Over the past decade, MRSA strains have become serious pathogens that are resistant to antibacterial therapy and have spread to many regions of the world. Therefore, the rapid detection and diagnosis of MRSA is important to improve treatment outcomes, prevent the spread of infection, and reduce the risk of patient mortality.

Staphylococcal enterotoxins are the most important cause of foodborne illness [34]. Enterotoxins are highly stable toxins that are resistant to proteolytic enzymes such as pepsin, trypsin, and chymotrypsin. The heat resistance of enterotoxins vary depending on the pH and salt concentration of the environment, but on average, these toxins can withstand an environment at 100 °C for 30 min [36].

When meat contaminated with S. aureus is undercooked or stored at inappropriate temperatures, enterotoxins accumulate and cause staphylococcal food poisoning. In a study conducted in Taiwan from 2001 to 2003, tsst (59.1%), sea (29.2%), and sed (2%) were identified in 147 of the S. aureus strains found in patients that were associated with staphylococcal food poisoning outbreaks [37]. According to Sarrafzadeh's study, more than 50% of food poisoning caused by staphylococci was caused by enterotoxin A [38].

In our study, tsst was found in 17.1% of the samples, sea in 17.1%, and sed in 2.9%, which indicates the risk of food poisoning caused by S. aureus enterotoxin in our country. According to Hoveida L 's study, enterotoxins were found in 20.5% of the meat samples in which S. aureus was detected, and the virulence genes sec (19%), sea (9.5%), and tsst (3.5%) were identified [39]. In the study by Manisha in 2000, 24.3% of the S. aureus were positive for tsst, and 19.6% were positive for sea [40]. According to our study, enterotoxin A (sea) and toxic shock syndrome toxin (tsst) were each present in 17.1% (6/35) of the samples, exotoxin A was in 5.7% (2/35), and type b was in 11.4% (4/35), while enterotoxin D (sed) was detected in 2.9% (1/35), which is similar to the results of previous researchers.

Identifying the comparison of the virulence genes detection between antibiotic resistant and susceptibility strain groups, there were no statistically significant differences between the two groups in this study. Similarly, the toxin or virulence genes were tested in the resistant strains and it has not been identified in half of the resistant strains [41]. The study of virulence genes differences between MRSA and Methicillin-susceptible S. aureus (MSSA) reported that the virulence genes such as sea gene were higher in MRSA isolates, but tsst genes were not statistically significant difference both groups [42]. On the other hand, the prevalence of sed and tsst genes was significantly higher in MRSA than MSSA isolates by the study of comparative analysis of the prevalence of virulence genes between MRSA and MSSA isolates using the Chi-square and Fisher’s exact test [43]. The difference of previous and study results might depend on the isolated strain, its virulence, sample type and size for isolating S. aureus and geographical areas.

Food contaminated with highly toxic and antibiotic-resistant S. aureus, especially MRSA, can pose a serious threat to public health. An effective reduction of staphylococcal contamination levels could be achieved by improving sanitation and hygiene procedures. Therefore, there is an urgent need to develop methods and strategies to control hygiene when handling retail meat, prevent bacterial contamination, and detect contamination quickly.

Also, the contact between processed foods and unprocessed foods must be avoided. In order to ensure food safety, there is a need to expand research on detecting virulence factors responsible for food poisoning and antibiotic resistance. Prudent use of antibiotics in veterinary medicine is recommended and also education on the proper use of antibiotics should be prioritized for livestock farmers.