Abstract
* Objectives: Isolation and Identification of S.aureus and study their susceptibility to the production of virulence factors.
 * Methods: A total of 50 clinical specimens of Staphylococcus aureus isolates were collected in AL- Najaf AL-Asharaf governorate during the period of (10/10/2013-20/1/2014) by the cultural characteristic colonies, microscopic for cells, biochemical tests, antibiotics susceptibility test to Staphylococcus aureus using an antibiotic diffusion disc assay, in addition to studying the virulence factors produced from S.aureus .
 * Results: The results show that the Staphylococcus aureus resistant to methicillin formed 70% and 30% of isolates were sensitive to the same antibiotics. Tested 10 isolates to methicillin-resistant for their efficiency in forming the highest inhibitory areas for testing their sensitivity to other antibiotics used, the results show S.aureus resistant to penicillin about 100%, while there is no resistance to CO-Trimethoprim because it was sensitive completely 100%.
 The susceptibility investigated of Staphylococcus aureus resistance methicillin isolates to the production of biofilm and slime layer with using both tube method and growth on Congo red agar respectively. Ten isolates of S.aureus were tested based on resistance to methicillin and their high susceptibility to the production of the biofilm and the slime layer.
 * Conclusion: So we conclude, they have Staphylococcus aureus is highly resistant to β- Lactam antibiotics and the CO-trimethoprim is the most effective in the inhibiting growth of this bacteria. In addition to its ability to produce virulence factors. The increase cause bacterial resistance to our local isolates may be due to the frequent use of antibiotics, which allowed for increased bacterial resistance to various antibiotics.
Highlights
In recent years, there has been an alarming increase in hospital-related infections caused by multidrugresistant Staphylococcus strains, Shown some strains have no resistance to more than 20 antibacterial compounds, including antiseptics[1]
The widespread clinical use of antibiotics leads to a high increase in resistance, especially among people are in hospital [32].Other studies have shown that Community Acquired Methicillin Resistance Staphylococcus aureus (CA-MRSA) have the ability to spread their colonies more than the Healthy Acquired Methicillin Resistance Staphylococcus aureus (HAMRSA), and this variability is due to the CA-MRSA contain psm-mec gene responsible for the spread of colonies and causing damage [27]
MRSA was detected the ability in the production of the slime layer using Congo-red agar described by the scientist [35]. 10 isolates were detected from MRSA, The results showed that 8 isolates of MRSA to change in developing colony color on the Congo- red agar from red to black or gray while the remaining two isolates did not show any change in the color of the medium, This indicates that these isolates were not production of the slime layer, as shown in Figure (5)
Summary
Growth S.aureus isolates on Mannitol salt agar aerobically by changing the color of the medium from pink to yellow due to their ability to ferment mannitol sugar and some isolates did not change The color of the medium due to inability to ferment mannitol sugar, which is consistent with [12]. Studies have documented thickening of the bacterial cell wall that traps the vancomycin molecules a decrease in peptidoglycan cross-linkage and a high content of free D-alanine-D-alanine residues in the cell wall may increase the resistance of the strain, a resistance resulting from the transmission of coded genes to the resistance characteristic of this antibiotic and portable to conjugated plasmids or transposon genes from other strains and species of bacteria S.aureus, giving it a resistance within a short period [22] It is effective against Staphylococcus aureus, it has been reported to be resistant to it, which may be due to increased cell wall thickness and decrease cell wall sensitivity to the analyze enzymes [23]. Several studies have confirmed the resistance of Staphylococcus aureus to penicillin [16] which found that the bacteria strain of penicillin resistant with ratio (100%), as well as the study by [27] Show result not found of efficiency to the penicillin against S. aureus. [28] noted that the cause resistance of S. aureus to penicillin is due to its production of penicillinase enzymes as shown in Figure (4)
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