الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 106 |  |  |
| | | from | 106 | | |
Abstract
MRSA in the last decades became one from most dangerous bacteria in hospitals, especially between weakness immune system patients such as diabetic patients and cancer patients furthermore increasing in infection between neonates, and increasing in mortality around the countries world this due to MRSA strain is remarkable with unique transposable elements called Staphylococcal Cassette chromosome mec (SCCmec) which is integrated in S. aureus chromosome which carrier for resistance gene called Mec A gene which give resistance for β lactam group including methicillin, MRSA strain prevalence rapidly not in hospitals alone but also in communities.
So that in our study mecA gene was detected among fifty random Staphylococcus aureus isolates, collected from different clinical samples (Blood-urine-sputum-pus-ascetic fluid-wound- abscess),these isolates were taken from different age groups (3 months-88 years) and collected from Microbiology department, Ain Shams University hospital, during 3Months period from March to July.
Biochemical and microbiological tests were performed which included all the isolates were streaked on Baired Parker media, catalase test, gram stained. DNA was extracted from all isolates and PCR was performed by specific primer pairs for mec A gene, Methicillin resistance S. aureus (MRSA) isolates were represented 68% whereas Methicillin Sensitive S. aureus (MSSA) isolates were represented 32%, also MRSA isolates were determined by sensitivity test (Cefoxitin disc) test represented 64%, and by (Oxacillin disc) test, represented 62%. This study was carried out at Ain Shams Center of Genetic Engineering and Biotechnology microbial laboratory (ACGEB).
Second objective in this study based on study if Staphylococcus aureus is mutagenicity bacterium or not, genotoxicity assay in this study was performed by two reliable genetic methods, comet assay and micronucleus test, forty five male mice were divided to nine groups, each group contain on five replicates and injecting with different seven isolates from MRSA beside one isolate from MSSA ,plus control group was injected by saline. liver and bone marrow were harvest after mice sacrifice for comet assay and micronucleus test respectively, These assays revealed 24% - 22% DNA damage as an indicate for chromosomal breakage by comet and micronucleus assays respectively, furthermore in the comet parameters, there were significant differences between MRSA,MSSA isolates compared with the negative control (saline) .
Three different types from damaged were seen in the DNA by comet assay (sample-medium-severe). We can say that S. aureus with its sensitivity or resistant strain to the antibiotics (in this case, methicillin) had ability damage the DNA
Mice bone marrow were examined by micronucleus test and micronucleated polychromatic erythrocyte cells (MnPCE) were shown, micronucleus test usually follows the comet assay to confirm its results Comet assay and micronucleus test performed at National Research Center (NCR) –Dokki-Giza – Egypt, and this part of the study was approved by the Ethical Committee of Animal Research in NCR. The results which were obtained from mutagenicity assay for our Egyptian isolates indicated that these isolates had ability cause mutations and chromosomal breakage and change in DNA.
so that after this study we can propose some suggestions that limited prevalence this bacterium such as Extensive Survey in Hospitals and communities to cover the spread (MRSA-VRSA-MSAA) isolates, also we must be interested by infection control programs in hospitals and can be develop a construct of hybrid Vaccines against MRSA strains approach, and we can focused on Plant extracts in treatment due to the ineffectiveness of most of the antibiotics currently present to the ability of bacteria to gain resistance to other types of antibiotics, and in the end due to the prevalence MRSA strain in Egypt ,it is necessary to take precautions in hospitals to prevent the spread of infection by HA-MRSA strain, and should reduce the excessive use of antibiotics to limited from the spread of these strains resistant.