S Aureus Strains In Food Biology Essay


The genome of staphylococcal usually encodes for several types of enterotoxin that are located on various mobile genetic elements, such as plasmids, prophages, and staphylococcal pathogenic islands (SaPIs) that are responsible for the horizontal transfer of virulence or antibiotic resistence genes between the strains of S. aureus. The seg and sei will code for SEIG and SEII that are present together in S. aureus (Vasconcelos et al., 2010).

The enterotoxin gene cluster (egc) known as the gene seg and sei with sem, se and seo, will encode for SEIM, SEIN, and SEIO that are present in an operon. Staphylococcal pathogenicity islands (SaPIs) are the enterotoxin-like superantigens that are encoded in the genetic elements of well-defined structure. These elements encoded repertoire of toxin genes seems to be specified (Vasconcelos et al., 2010).

2.4.1 Molecular method (multiplex PCR) for the detection of staphylococcal enterotoxins genes present in food sample

The multiplex PCR method is a widespread molecular biology technique for amplification of multiple targets in a single PCR experiment. In a multiplexing assay, more than one target sequence can be amplified by using multiple primer pairs in a reaction mixture. Besides, the multiplex PCR method was decribed for the typing S. aureus toxins. This instrument function is based on combinations of specific primers for gene se or on combinations of universal forward primers with specific reverse primers and it is a technique in which different types of enterotoxin genes are detected in a single procedure (Vasconcelos et al., 2010).

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Morandi et al. (2007) had done a study to analyze the genes encoding sea, sec, sed, seg, seh, sei, sej, and sel among staphylococcal enterotoxins (SEs) in S. aureus that were isolated from different types of food including bovine, goat, sheep, buffalo milk and dairy product. Polymerase Chain Reaction (PCR) was used for detection.

A total of 112 S. aureus strains were isolated from 86 raw milk samples and 26 raw milk sample products that originated from different regions in Italy and species of animals. Baird Parker agar along with rabbit plasma fibrinogen supplement incubated for 24 to 48hr at 37oC to isolate the strains and detect the coagulase-positive S. aureus. Gram staining, catalase activity determination and heat stable nuclease (TNase) test using Toluidine blue agar to identify the isolates from food samples was carried out by Morandi et al. (2007). VIDAS SET test and SET-RPLA were used to detect different types of enterotoxins in this study (Morandi et al., 2007).

The result of Morandi et al. (2007) showed that a total of 112 isolates belonged to S. aureus by mPCR reaction. Table 21 showed the presence of se genes in S. aureus isolates and 75/112 (67%) of S. aureus isolates show positive result of more than one type of toxin genes and also marked genotype variability that were categorized into 17 different groups related to gene presence. 16 cows, 4 goats and 1 isolated from buffalo made up 21 strains that possessed one types of toxin gene include 13 sea, 2 sed, 1 seg, 3 seh, and 1 sei, while the remaining of 55 encoded more than one type of toxin gene.

Among 75 se positive isolates, 19 (25%) of the S. aureus enterotoxins producers (17 cow and 2 goats) producing classical se, while the newly described se (seg-sel) produced by 8 positive strains (6 cow and 2 sheep sample). Beside that, they also found out 64% of the strains produced classical and new se in combination (31 from cow, 10 from goat and 7 from sheep dairy product) (Morandi et al., 2007).

Table 22 shows S. aureus isolate strains from goat product that had the only classical enterotoxin gene, classical and new enterotoxin gene while none of the other had the new enterotoxin gene. Only 6 from goat isolates and 2 from sheep sample that showed positive for seg, seh, sei, sej and sel. The seg and sei gene were detected in 2/6 of cow isolates, 3 in the seh and 1 in the sei genes as well. While the seg and seg-i genes were found to be present in the two strains of sheep products (Morandi et al., 2007).

Morandi et al. (2007) compared the data of strains isolated from different samples, the enterotoxin sea, sed and sej were frequently found in 54/71 (76%) cow strains that showed positive to se. While in goat dairy product they detected 12 of the 22 S .aureus (55%) strains that harboured sec and sel that found in 7 strains. sec and sel were commonly detected in S. aureus strains that were isolated from sheep among the 53% isolates. However, two strains that were isolated from buffalo did not produce any SEs.

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Morandi et al. (2007) had reported that the SEs and se genes was in close correlation with the S. aureus strain origin, a higher ratio of strains isolated from cow producing SEA, SED and sej, while the strains from goat and sheep produced mainly SEC and sel. The strains of S. aureus that were isolated from all the samples had higher heterogenous enterotoxigenic potential that could lead to food poisoning.

On the other hand, another study was done by Rall et al. (2008) in the Assis city area, in west of Sao Paulo State, Brazil to analyze the prevalence of the genes encoding the staphylococcal enterotoxins (SEs) SEA, SEB, SEC, SED, SEE, SEG, SHE, SEI and SEJ present in S. aureus strains. These were isolated from raw and pasteurized milk. In this study, they collected 54 bulk tank milk sample from the farm and a total of 162 samples was analyzed.

In this experiment, Rall et al. (2008) used serial dilutions of mik homogenates and plated on Baird Parker agar along with 5% egg yolk tellurite emulsion and incubated. The Voges-Proskauer (VP) test was used to distinguish between S. aureus (positive) and S. intermidius (negative) during S. aureus isolation and identification process. For DNA isolation, they used a commercial kit (GF; GE healthcare) and primers used for detection of genes as well.

The result shows 39/57 (68.4%) were positive for one or more SE genes among the 12 different types of genotype profile present in 57 strains of S. aureus. Among the positive strains in this study as shown in table 22, Rall et al. (2008) found 27/38 (71.1%) of the raw milk isolate tocarry one or more than one type of toxin. While for the percentages of positive strain for the SE gene in pasteurized milk tested before and after expiration date was 62.5% (5 of 8 isolates) and 63.6% (7 of 11 isolates) respectively (Rall et al., 2008)

Among the SEs gene identified by Rall et al. (2008), they found out only 25 strains (64.1%) were harboured one enterotoxin gene, while 9 (23.1%) carried genes encoding for two enterotoxins and(sea+sec+seh) were showing positive accounted for 5.1% (2). Only three isolate strains (7.7%) were positive for gene encoding four enterotoxins (sea+seg+sei+sej, sea+sed+seg+sei and seb+seg+she+sei). They found gene encoding enterotoxins SEH, SEI and SEJ only exist in combination in these study.

Among the genes that code for classic enterotoxins (SEA-SEE), sea was the most frequent; it was found in16 isolates (41%), followed by sec in 8 (20.5%), sed in 5 (12.8%), seb in 3 (7.7%) and see in 2 (5.1%) strains. Regarding the other enterotoxins, the new enterotoxins seg was found most frequently in the 11 strains (28.2%), followed by sei in 10(25.6%), seh and sej in three strains each accounted for 7.7% as shown in the table 23 (Rall et al., 2008).

Rall et al. (2008) stated that SEA was the most common type of staphylococcal enterotoxin present in enterotoxigenic strains of S. aureus in this study. The percentage of potentially enterotoxigenic of S. aureus strains will increase with the new discovery of enterotoxins. In this study, 39 (68.4%) strains were positive for the presence of at least one SE gene; however, that number would drop to 31 (52.5%) if only the classic enterotoxins (sea to see) were considered.

seg gene was frequently associated with sei that was detected in 10 isolates (25.6%) in this study due to themselves located within the same cluster in a 3.2 kb DNA fragment and carried by the same plasmid. In this study, Rall et al. (2008) able to detect genes encode for classic and also newly described enterotoxins in S. aureus strains isolated from milk at different stages showing increased the number of enterotoxigenc staphylococci isolate that lead to greater pathogenic of S. aureus in all food product (Rall et al., 2008).

On the other hand, Pereira et al. (2009) had conducted a research on characterization of different S. aureus isolates from different food products that were collected from the north of Portugal, This characterization was based on the ability of the isolates to produce and toexpress staphylococcal enterotoxins, on the antibiotic susceptibilities in order to determine the presence of MRSA strains, and on the presence of other virulence factors. Different food products from 2006 to 2008 were sent to microbiological lab tested for presence of coagulase-positive staphylococci. Pereira et al. (2009) used VIDAS methodology and multiplex PCR to study the S. aureus strains for their ability to produce enterotoxins and also the presence of enterotoxins genes among the one hundred and forty seven strains.

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From the result, Pereira et al. (2009) showed that among the S. aureus isolates strains, the VIDAS tests showed that 40% of the tested strains isolated from fermented sausage product were enterotoxigenic and only 1 and 3 isolates of the S. aureus strains from bovine mastitis and raw milk were showed enterotoxigenic respectively as shown in the table 24.

Beside that, for the result of SE production and se genes detection by multiplex PCR analysis among the 148 strains of S. aureus indicates that 69% of them carried more than one type of genes and 88% of them possessed more than one se genes. sea, seg, sea seg sei and seg sei were detected genes among the eleven se genotypes accounted for 26%, 23% and 25%. On the other hand, strains isolated from fermented products showed the highest incidence types of enterotoxins as compared to isolate from the rest of the food product (Pereira et al., 2009).

Pereira et al. (2009) had shown the frequent detection of sea, seg and sei genes among the S. aureus strains were heavily linked to food-poisoning outbreaks in these cases.However, the VIDAS tests can only detect the expression of SEA-SEE and also indicate either positive or negative result about the expression of the SE toxins A-E which does not discriminate between them as compared to multiplex PCR (Pereira et al., 2009).

Ertas et al. (2010) used multiplex PCR (mPCR) technique to investigate the existence of S. aureus and staphylococcal enterotoxins (SEs) genes present in both sheep cheeses and dairy dessert samples. In this study, they analyzed 150 of food samples that included 50 from dairy dessert and 100 from sheep cheese that were collected and purchased from different places between August to December 2009 in Kayseri in Turkey. They used Baird Parker Medium along with 5% of egg yolk and tellurite and incubated at 37 o C for 24 hours to isolate the S. aureus strains. Colonies with a black appearance that surrounded by clear zone were identified as S. aureus strains.

Five of the isolates were identified that originated from both samples were transferred to the blood agar and subjected for Gram coloration, coagulase, catalase, oxidase and urease test. In this study, Pereira et al. (2009) also used Enzyme-Linked immunosorbent Assay (ELISA) technique and primers along with PCR assay for detection of SEs and identification of the sea, seb, sec and sed gene sequence.

The result of Ertas et al. (2010) showed that 86/150 (57.3%) of the analyzed sample were contaminated with Coagulase-positive staphylococci (CPS) that originated from 60 (40%) and 26 (17.3%) of the sheep cheese and dairy product as well. The total S. aureus counts determined on BPM (Oxoid) were fell within the range 1 - 102 and 1 - 106 CFU/g in sheep cheese and dairy dessert samples. In 25 (25%) of sheep cheese and 12 (24%) dairy dessert samples, CPS counts were above 105 CFU/g. 86 samples showed positive among the 430 isolates, 300 from cheese and 130 dairy desserts in this study. Total of CPS isolate 80 (18.6%) strains were S. aureus followed by 60 (20%) from the cheese and 20 (15.3%) from dairy product as shown in table 25.

The ability to synthesize enterotoxins was determined in 12 (2.8%) out of 80 isolates by using ELISA technique. It was determined that these SEs had a distribution of 7 (1.6%) SEA, 2 (0.46%) SEB, 1 (0.23%) SEC, and 2 (2.3%) SED in this study. Staphylococcal enterotoxin types A present in 4 (1.3%) cheese and 3 (2.3%) of the dairy dessert samples. They found only in 2 (0.6%) and 1 (0.76%) of dairy dessert and cheese sample produce type B and type C enterotoxins respectively. Toxin types D was found in 1 (0.3%) cheese and 1 (0.76%) of dairy dessert samples as shown in table 26 (Ertas et al., 2010).

Ertas et al. (2010) used mPCR in this study to detect different types of SEs genes were presented in 13 (3.02%) among the 80 isolates. It was identified that these enterotoxins contained 8 (1.8%) sea, 2 (0.46%) seb, 1 (0.23%) sec, and 2 (0.46%) sed gene distribution. Among the cheese isolates, sea was detected in 5 (1.6%) isolates, seb in 2 (0.6%) isolates and sed in 1 (0.3%) of the isolates. Beside among the dairy dessert isolates, they identified sea in 3 (2.3%) isolates, sec in 1 (0.76%) isolates and sed in 1 (0.76%) of isolates. These toxins were only found in 3 (2.3%), 1 (0.76%) and 1 (0.76%) of tavuk gogsu, keskul and kazandibi samples, respectively. There were no SEs were found in sutlac and supangle as shown in table 26.

Ertas et al. (2010) had done a research on the detection of enterotoxigenic S. aureus that present in dairy desserts and sheep cheese. The result shown the 25 (25%) of sheep cheese samples in which the S. aureus count was identified fall above 104 CFU/g. While in enterotoxin-producing capacity 7/60 (2.3%) of sheep cheese isolates was identified by ELISA technique. 4 (1.3%) SEA and 2 (0.6%) SEB and 1 (0.3%) SED were the SEs genes that identified only in 8 (2.6%) of 300 sheep isolates. (Ertas et al., 2010) found mainly enterotoxin gene sea, seb and sed genes in sheep cheese isolates.

Besides, S. aureus count was found above 105 CFU/g in 12 dairy desserts which were one of the traditional products in Turkey. ELISA technique found out 5/20 dairy dessert isolates had the ability of producing enterotoxins in which these SEs had a distribution of 3 (2.3%) SEA and 1 (0.76%) SEC and 1 (0.76%) SED. Among the enterotoxin gene, se (sea, sec and sed) genes were found mainly in 5 of the dairy dessert samples as shown in figure 5 and table 26 (Ertas et al., 2010).

In figure 5 it showed Lane M indicated molecular weight marker (Gene RulerTM 50 bp DNA Ladder Plus, Fermentas); lane P1 indicated positive control for sea (S. aureus ATCC 29231, 270 bp), lane P2 indicated positive control for seb (S. aureus NCTC 10654, 165 bp), lane P3 indicated positive control for sec (S. aureus, NCTC 10655, 69 bp), lane P4 indicated positive control for sed (S. aureus NCTC 10652, 306 bp), lane N indicated Negative control (H2O), lane 1-3 indicated sheep cheese isolates, sea. Lane 4-5 indicated sheep cheese isolates, seb. Lane 6-7 indicated sheep cheese isolates, sea. Lane 8 indicated sheep cheese isolates, sed. Lane 9-11 indicated dairy dessert isolates, sea, lane 12 indicated dairy dessert isolates, sec, lane 13 indicated dairy dessert isolates, sed (Ertas et al., 2010).

The prevalence of S. aureus count and SEs in dairy dessert samples is much lower compared to sheep cheese mainly due to the cheese have made from raw milk which were the sources of staphylococcal food poisoning. During cheese production, bacteria are able to invade and contaminate the milk and product material from the equipment and the environment (Ertas et al., 2010).

Morandi et al. (2007), Pereira et al. (2009) and Ertas et al. (2010) showed that different types of se gene encodes different types of SE enterotoxins in different types of food product worldwide. Each of them plays a major role in food poisoning outbreak as S. aureus had the potentially pathogenic role as a food-borne pathogens.

Table 21: The distribution of se genes and SE production in S. aureus according to the origin of the isolates

(Morandi et al., 2007)

Table 22: The distribution of sea-sel genes in 75 S.aureus strains according to the origin

of isolates

(Morandi et al., 2007)

Table 23: The genotypic profile of S. aureus strains, isolated from raw and pasteurized milk, according to different types of SEs genes

(Rall et al., 2008)

Table 24: The enterotoxin genes distribution among the S. aureus isolates

(Pereira et al., 2009)

Table 25: The distribution of S. aureus in sheep cheese and dairy desserts (CFU/g)

(Ertas et al., 2010)

Table 26: The occurrence of SEs genes in S. aureus isolates from samples.

(Ertas et al., 2010)

Figure 5: Identification of S. aureus enterotoxin genes from sheep cheese and dairy desserts by multiplex PCR.

(Ertas et al., 2010)

Molecular method (Pulsed-field gel electrophoresis) for the S. aureus genotyping

PFGE is one of the technique used to separate the relatively large pieces of

deoxyribonucleic acid (DNA) molecules by applying an electric field that periodically

changes direction to a gel matrix. Besides, it is known as 'gold technique' technique to

determine the genetic relatedness of SEs that presented in different types of food products

especially during outbreaks.

Aydin et al. (2011) had done a study to determine the frequency of PTSAgs including SE geness (sea, seb, sec, sed and see), SEI genes (seg, seh, sei, sej, sek, sel, sem, sen, seo, sep, seq and seu),, tst and exofoliative genes (eta and etb) among the S. aureus isolates. The PFGE was used to determine the ability of the isolates to produce different types of SEs and the genetic-relatedness of enterotoxigenic strains in the Marmara Region of Turkey. 1070 food samples were collected and analyzed from the retail market and dairy farms to detect the presence of S. aureus bacteria within the period of July 2007 and December 2008. EN ISO 6881-1 standard procedures were used to isolates the S. aureus that present in food samples.

The monoplex and multiplex PCR was used to determine the presence of Staphylococcal

enterotoxin genes, genes for exfoliative toxins and toxic shock syndrome toxin (tst). The

PCR product was dissolved in 1.5% of the agarose gel electrophoresis in 1xTAE buffer

(0.04M Tris-acetate and 0.001M EDTA). Each isolate were done twice by PCR. While for

the enterotoxin production was determined by using ELISA and Ridacreen SET A, B, C, D,

E assay kit. PFGE analysis was used to analyzed the genetic-relatedness of 92

enterotoxigenic S. aureus food isolates.

The result of Aydin et al. (2011) indicated that the among 1070 food samples isolated were

found the presence of 147 (13.8%) of S. aureus strains were analyzed for toxigenic

capabilities. 92 strains (62.6%) were isolated from meat (13/13), bakery product (6/6), raw

milk (31/63), dairy products (36/54), bakery products (5/9) and ready-to-eat foods (1/2)

were found to be enterotoxigenic that is capable of producing SEs as shown in table

In this study, 53.3% of the isolates show negative for sea to see carried SEI genes among

the 17 SE and SEI genes investigated. It shows relatively high percentages of SEI genes as

compared to classical SE genes. While only 8.6% of the enterotoxigenic strains were found

encode only one types of sea. The single enterotoxigenic gene sep was the highest (13%)

that was detected in 19 (20.7%) S. aureus strains mostly found in dairy product (n=8) and

raw milk (n=7) . While for seb genes was found in 5 (5.4%) S. aureus isolates mainly in

meat and dairy product. All sek-positive isolates (HE4D, S133A, YF62A, YFG2B) showed

positive for seq, while sek does not present in 4 seq-positive isolates (PY38BY/1,

PY92BY/2, S137AY, and TEI5A). These results shown sed, see and sej does not present

among the enterotoxigenic strains as shown in table (Aydin et al., 2011).

Besides, two isolates (PY178A and PY178B) from dairy product were found contained sec,

sel and sep and sec and sel genes were found only in two isolates (HE25A and HE25B). In

this study, only sec genes present in 27.2% of enterotoxigenic S. aureus isolates and only 8%

of them carry sel gene. All the positive isolates (n=28) were also positive for sei. While 3

isolates (EU6A, PY178A, S226) containing sei but does not found the presence of seg gene.

Almost all the strains (29.4%) in this study were found contained seu gene and combination

with other enterotoxin genes. For seh genes were found only in 8 (8.6%) of the isolates and

totally in 15 (16.3%) of the isolates seh and seh combination with other genes were

detected (Aydin et al., 2011).

In this study, 46.7% of S. aureus isolates were found possessed the target classical SEs

genes (sea, seb, sec). ELISA detected 72.1% of the enterotoxigenic S. aureus isolates

produced enterotoxin SEA-SED. Only 2, 8 and 10 of the isolates produced only SEB, SEA

and SEC, while 11 of the isolates produced more than one type of enterotoxins. This

indicated there was a 72.1% close relationship between the types of enterotoxins and SEs

genes (Aydin et al., 2011).

Based on the ELISA results, 4 of the isolates (TE2, EU7A, S272, PY186A) produced SEC,

while 8 of the isolates produced only SED. PCR does not detect any presence of sed and

sec in these isolates. 3 isolates were positive for SEC, SEC and SED, while SED was found

in 5 isolates. Moreover, one isolates (S158B) that produced SEB and SEC showed negative

result for the presence of seb, but positive result for sec and SEI genes. While none of the S.

aureus was found contained eta and etb genes (Aydin et al., 2011).

The PFGE analysis was carried out by the digestion of enterotoxigenic S. aureus strains

DNA with Smal as restriction enzyme to produced 9 to 15 different fragments and the band

pattern produced were compared. The genetic relatedness of 8 sea-, 10 sec-, 8 seh- and 15

sep-positive isolates were shown in figure ( ). (PY104A, PY104B and PY311B) were

three isolates come from dairy products and two isolates (S272 and S273) from raw milk

samples showed 100% homology with similar band patterns. While other sea-positive

isolated showed 72 to 86% homology as shown in figure ( A). Figure ( B) showed the band

pattern of ten sec-positive isolates displayed 61 to 90% homology.While for the band

patterns of seh-positive isolates, 2 isolates (PY38BY/2 and S4BY) from dairy products and

raw milk displayed 100% homology. The remaining isolates from dairy product and meat

were showed (80-96% homology) in figure ( C). (S15A, S15B, S15C and S15D) isolates

from raw milk samples and (PY330A and PY330B) isolates displayed the same band

pattern. 100% homology pattern can be seen from (PY192A and PY245B) from dairy

product that collected from two different cities. Most of the isolates from raw milk and

dairy product contained the sep-gene (Aydin et al., 2011).

Figure ( ) showed genetic-relatedness of S. aureus isolate that containing multi

enterotoxin genes. Among the isolates, 3 isolates (PY128A, PY128C and PY128D) and

other 6 group of isolates (EU6B and EU6C, EU7A and EU7B, HE25A and HE25B, PY31A

and PY31C, S25A and S35B, S143A and S143B) showed 100% homology mainly come

from meat products, raw milk and dairy products. The same genes that were closely related

present in isolates will displayed more than 80% homology (Aydin et al., 2011).

Figure ( ) signify the genetic relatedness of 9 tst-positive isolates. The prevalence of tst

gene, 9.8% of the S. aureus isolates were showed positive for tst. Two main groups made

up the dendrogram of tst-positive isolates that displayed 74% homology. (EU6A, EU6B

and EU6C) isolates and (EU7A and EU7B) isolated from meat products showed 100%

homology. While S. aureus isolates (YF75B) and PY2 isolated from bakery product and

dairy product displayed 94% homology that collected in different cities. The 2 remaining

isolates which were isolated from dairy products in Tstanbul, displayed 90% homology. All

the tst-positive S. aureus isolates are closely related with each other with more than 74%

homology (Aydin et al., 2011).

The discovery of new SEs leads to increased frequency of potentially enterotoxigenic S.

aureus strains from food products will lead to food poisoning. Additional work is necessary

to had better understanding the mechanism of S. aureus in food poisoining and minotoring

the presence of genes in food isolates.The PFGE analysis displayed a high genetic

relatedness among strains isolated from different types of food products, indicating that

contamination of food with the bacteria come from various sources, processing place and

environment as well as the market place (Aydin et al., 2011).

3.0 General discussion

Staphylococcal food poisoning (SPF) is one of the major concern in public health around the world in which cause of increased patient morbidity and mortality. Besides, it is a considerable social burden in terms of hospital expenses, loss of patients' working days and productivity and the cost of disposing contaminated foods. The term staphylococcal refers to S. aureus bacterium that presents in food product that induces its toxicity in food. In general, SPF is serious cases as compared to other foodborne infection due to the S. aureus are virulent and antibiotic resistant that capable to produce a wide variety of virulence factors that caused a large spectrum of infections (Normanno et al., 2005).

Identification and quantification of coagulase positive isolate in end products used to determine the microbial risk assessment for S. aureus in most countries. As this bacterium is widely distributed in raw ingredients and low contamination level does not induce foodborne infection, the microbial norms in most countries tolerate S. aureus contamination. Heat treatment can easily eliminate S. aureus from the foodstuff especially in pasteurized foods or by competition with other flora. However, the SEs usually resist most of the treatment during the food preparation which remains intact inside the foodstuff (Loir et al., 2003).

MRSA is the most common antibiotic resistant bacterium which contains mecA gene that encodes the penicillin binding protein with low affinities for β-lactam antibiotics. S. aureus is often found in foods of animal origin that produced and market at different places (Normanno et al., 2007).

Consumption of food that is contaminated with MRSA bacterium that can easily transmit to human beings via the animal derived-food product. Small amount of MRSA present in foods of animal origin may cause a risk for customers as well as immunocompromised individuals. The specific and non-specific immune response of immunocompromised individuals not able to serves as a barrier to prevent the colonization of the gastrointestinal tract and consumption of food that is contaminated with MRSA may cause lethal disease. By improving the hygiene in food production and warrants the microbiological controls of food product to minimize the wide spread of MRSA and the other antibiotic-resistant microorganism via the food product (Normanno et al., 2007).

On the other hands, staphylococcal enterotoxin A and staphylococcal enterotoxin D are the most frequently related to food poisoning due to their ability to produce in a wide range of growth conditions. With the advanced technology, the discovery and characterization of new SEs lead to an increased frequency of potentially enterotoxigenic S. aureus isolated from foods had the high prevalence pathogenic S. aureus are higher than the existing SEs. The high occurrence of new enterotoxin genes were commonly found in foodborne isolates that contributing to the prevalence of isolates capable of causing food poisoning. Additional work and research are necessary to have a better understanding the role of S. aureus in foodborne infection and also minimize the presence of new genes in foodborne isolates (Bhatia et al., 2007).

Molecular techniques are important tools which aid in the detection and investigation of outbreaks and epidemiology of foodborne pathogens. Besides, they capable of understanding the complex genetics of virulence mechanism of microorganism and determine the pathogenic potential of isolates by observing the presence of virulence factors encoding genes and their expression. The multiplex PCR can be used to detect SAg genes in S. aureus that isolated from different types of sources. Besides, it is able to provide information about the SAgs genes as well as a mobile genetic element in order to have a better understanding about the evolution of S. aureus as a pathogenic microorganism (Vasconcelos et al., 2010).

4.0 Conclusion

Based on the literature studied, it was found that Staphylococcus aureus and MRSA present in all sort of food products which may produce staphylococcal enterotoxins (SEs) that lead to food intoxication. The present of SEs can be detected in order to avoid the spread of the disease that causes major hazard health of human being. As a result, food should be handled in the proper way and all the hygiene measures should be practiced so that all the food product is safe for all the consumers.