الفهرس 
Review of literatures
4. Prevalence of MRSA and VRSA in some milk productsOnly 14 pages are availabe for public view
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Abstract
Dairy products are common, digestible and nutrient-rich food that contain protein, carbohydrates, lipids and micronutrients, which are vital for human health. The involvement of these products in the daily healthy diet improves people’s well-being.
Dairy products serve as very good medium for the growth of many microorganisms including Staph. aureus leading to foodborne illness, public health hazards and economic losses.
A total of 150 random samples of Tallaga cheese, Small scale ice cream and Locally made yoghurt (50 of each) were collected based on their availability in the super market and diary shops located in Sohag city, Egypt for the isolation and identification of Staph. aureus.
The samples were submitted for conventional and molecular examination by traditional and molecular methods. Cultivation on culture media, Gram staining, biochemical reactions and antibiotic sensitivity test represented the conventional methods while amplification of coa gene represented the molecular identification method.
The obtained results showed that CPSA were detected in fifty five samples from totally collected 150 milk product samples (36.7%), CPSA from the examined samples were 22% (11/50), 58% (29/50), 30% (15/50), isolated from Tallaga cheese, Small scale ice cream, and Locally made yoghurt, respectively.
The antibiogram pattern of CPSA strains isolated from examined samples showed that isolated strains were resistance to methicillin (32.7%) and vancomycin (10.9%).
Regarding PCR confirmation, 6 phenotypically resistance MRSA and VRSA isolates were examined for detection of coa gene for more identification and detection of the virulence related to isolates. All examined strains were positive for the coa gene.
The influence of lemon grass and cinnamon oils and their nanoemulsions on the viability of resistance MRSA and VRSA strains inoculated in laboratory manufactured Tallaga cheese was detected. Lemon grass and cinnamon essential oils were purchased from National Research Center, Egypt. In addition, their nanoemulsions were prepared and characterized. The particle size and PDI of nanoemulsions are were measured by Zetasizer and the PDI were 0.426 and 0.480 for LGN and CN, respectively. PDI results indicated the stability of the prepared NEs.
Furthermore the morphology of the NEs was visualized by TEM analysis, the image revealed that most of the nano droplets were almost spherical in shape, with average size of 89.45 and 78.56 nm for LG and C NEs, respectively, which provides more antibacterial activity.
The MIC of the prepared lemon grass and cinnamon EOs and their nanoemulsions were detected in-vitro against the isolated resistance MRSA and VRSA strains by using agar well diffusion method, in which, the results revealed that the MIC were 1.56% for both EOs and their NEs.
Tallaga cheese were manufactured using MIC of the 2 prepared EOs and their NEs, before inoculation with isolated resistant MRSA and VRSA strains part from cheese were removed and kept as negative control and for organoleptic examination. The cheese were stored in sterile jars, stored at 4°C, and analyzed at zero time, after curdling, after 24hrs, third day, and day after day interval until un-detection of microorganism or deterioration of storage cheese. As well as, sensory analysis was performed periodically.
The applied in-vivo study reflected the effectiveness of the used EOs and their NEs against the inoculated pathogenic strains. The LGN was the most effective against resistant MRSA and VRSA strains in which the count decreased from 4.5 × 〖10〗^7 ± 1.7 × 〖10〗^7 at zero time to < 10 at 5^th day.
The sensory parameters of the manufactured cheese were of medium overall acceptability (OAA) in relation to the taste due to strong flavor of the used essential oil concentrations, while NEs was most preferable than their EOs and can be used in other dairy products as flavored fluid milk and dairy desserts to control the growth of Staph. aureus in the products.