br Materials and methods br Results

Materials and methods
Results and discussion All isolates produced PCR amplicon with the COAG2 and COAG3 primers (Fig. 1). The agarose gel analysis of the PCP inhibitor products showed ten different sizes, ranging from approximately 500 to 1000bp. The product sizes of 800, 900 and 850±20bp were the most frequent sizes, reported for 24, 20 and 19% of the isolates, respectively. There was no amplification product of the DNA from S. epidermidis. As summarized in Table 1, NdeI restriction enzyme digestion of the PCR products generated 18 different NdeI restriction patterns for all isolates. Except for the products of 500, 600 and 1000bp, amplicons of the same size generated different patterns, with the number of fragment varying from two to three and molecular sizes from approx. 80 to 330bp (Fig. 2). Types 9, 11 and 14 were the most common patterns and seen in 50% of the isolates (Table 2). Type 1 was the most frequent pattern and reported in 31.25% of meat product samples, while Type 9 was the most frequent pattern in other foods (50%). Coagulase protein is a main virulence factor in S. aureus[21]. The 3′ end of the coagulase gene contains a series of 81-bp tandem repeats, which is different between S. aureus strains [22]. Classification based on the RFLP of coa gene, has been considered as a simple and accurate method for typing S. aureus isolated from various sources [17,19]. Using this method, different genotypes were seen among the studied isolates, which suggest that S. aureus has a certain degree of heterogeneity in the food samples. The ten different PCR types and the 18 NdeI RFLP patterns suggest that the isolated S. aureus strains harbor more than one variant of the coa gene. Results also showed that however different genotypes were detected; only a few predominated. These findings were similar to findings published by researchers who tested milk of bovine mastitis in various countries [12,19,21–23] and showed that several coagulase gene types were responsible for the majority of bovine mastitis cases; only some were predominated in each country. El Bayomi et al. by Genotyping using spa PCR-RFLP showed identical restriction banding patterns of MRSA isolates of human and chicken meat origin, indicating the genetic relatedness of the isolates [19]. Aslantas et al. typed 80 S. aureus isolated from subclinical bovine mastitis milks and distinguished five PCR and nine RFLP types, with two most common genotypes reported for 73.8% of the isolates [22]. Guler et al. tested 125 S. aureus isolates from bovine clinical mastitis in Turkey and found four PCR products of 1000, 900, 800 and 700bp, with a 1000bp product being the predominant product [23]. Blaiotta et al. showed in some strains of Staphylococcus xylosus, Staphylococcus saprophyticus, and Staphylococcus equorum, two catalase genes, katA and katB, were found [24]. Kizerwetter-Swida et al. showed coagulase-positive staphylococci (CoPS) are opportunistic veterinary pathogens, of which S. aureus, Staphylococcus delphini and Staphylococcus intermedius can be isolated from pigeons. The biochemical identification of S. delphini and S. intermedius isolates may be incorrect, because of their phenotypic similarity. A total number of 31 isolates of CoPS was obtained, 15 were identified as S. delphini group B, six as S. aureus, four as S. delphini group A, three as S. intermedius and three as Staphylococcus schleiferi subsp. coagulans. PFGE restriction patterns of S. delphini group A and S. delphini group B form separate clusters, demonstrating their genetic heterogeneity [25]. Da Silva et al. tested 33 S. aureus from milk of goats with clinical and subclinical mastitis, belonging to two regions from Brazil and found 11 genotypes. One predominant type was found in each region in most of the isolates [26]. According to Hennekinne et al. Staphylococcal food poisoning (SFP) is one of the most common food-borne diseases caused by the ingestion of staphylococcal enterotoxins (SEs) produced in foods by enterotoxigenic S. aureus[27]. Similarly, Moon et al. typed S. aureus isolates from animal and vegetable sources in Korea and distinguished 12 genotypes, varied with the source of the microorganisms. However, only a few genotypes prevailed in each source [28]. This distribution might be explained by the coevolution of the hosts and the pathogens, and also differences in reservoirs and imply that the successful transfer of bacteria between bovine mastitis milk, raw meat and vegetables is not a frequent occurrence [22,27].