Staphylococcus aureus isolates were isolated from fifty clinical samples collected from Ain Shams University Hospitals (March-July 2016) and identified using biochemical and microbiological tests. PCR was performed using specific primers to determine the isolates of Methicillin-Resistant Staphylococcus aureus (MRSA) based on the presence of mecA gene. Thirty-four isolates from total fifty isolates (68%) were identified as MRSA isolates. To study the genotoxicity for this isolates, forty-five mice were injected with these MRSA isolates and comet and micronuclei assays were performed on mice liver tissues and bone marrow respectively. These assays revealed 24%-22% DNA damage as an indicator for chromosomal breakage by comet and micronucleus assays respectively which indicate that infection with these isolates leads to mutations. Studying these isolate furthermore will give an insight on how critical maintaining high standard hygiene in Egyptian hospitals and attention to infection control system can prevent occur of outbreaks

Objective: An attractive, well-balanced smile is a paramount treatment objective of modern orthodontic therapy. The purpose of this study was to compare changes in smile proportions among extraction and non-extraction therapy cases and to correlate them with the accompanying hard and soft tissue changes. Material and Methods: A sample of 24 patients with an age range of 14.3-24.9 years, requiring fixed orthodontic treatment was divided into group I (extraction therapy cases) and group II (nonextraction therapy cases). Dentofacial characteristics of the 2 groups were obtained from close up smile photographs and lateral cephalometric analyses before and after treatment.independent student "t" test to compare between both groups before and after treatment, Paired student "t" test to evaluate the change within the same group and Pearson's correlation analysis to evaluate correlations between selected parameters. Results: After treatment, maxillary incisor display showed significant increase in the nonextraction group also, maxillary gingival display showed significant increase in the extraction group (P < 0.05). When the two groups were compared, after treatment, the extraction group showed significant higher values in the posterior corridor ratio and maxillary gingival display (P < 0.05). The posterior corridor ratio was negatively correlated with lower anterior facial height (r = -0.579).The amount of incisor display during smile was positively correlated with the inclination of maxillary incisors in relation to the skull base U1/SN (°) (r = 0.499) and with maxillary incisors protrusion measured as U1/NA distance (r = 0.676). Conclusion: the results revealed that the extraction therapy cases showed higher values in the posterior corridor ratio and maxillary gingival display than the non extraction therapy cases. The significant relationship of incisor protrusion and inclination with the amount of incisor display and the significant relationship of lower anterior facial height with the posterior corridor ratio must be considered when planning orthodontic treatment