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Roghayeh Samadi,1 Zohreh Ghalavand,1 Reza Mirnejad,2 Bahram Nikmanesh,3 Gita Eslami1 1Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran; 2Molecular Biology Research Center, Systems Biology and Poisoning Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran; 3Department of Medical Laboratory Sciences, School of Allied Medical Sciences, Tehran University of Medical Sciences, Tehran, IranCorrespondence: Gita EslamiDepartment of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, IranTel +98-2123872556Email g_eslami@yahoo.comIntroduction: Methicillin-resistant Staphylococcus aureus (MRSA) causes high rates of mortality and a substantial burden to health systems worldwide. Here, we investigated the antimicrobial susceptibility and molecular characteristics of MRSA isolated from children referred to Children’s Medical Center in Tehran.Materials and methods: A total of 98 MRSA isolates were collected from children. Antimicrobial resistance patterns were determined using the disk diffusion and E-test methods. The presence of biofilm encoding genes and the pvl gene were determined by PCR. We used the microtiter plate method to assess the ability of biofilm formation. The MRSA isolates were further analyzed using PFGE and SCCmec typing.Results: Antibiotic susceptibility testing showed that the highest and the lowest antibiotic resistance percentage were related to erythromycin (62%) and minocycline (10%), respectively. Overall, 63% of MRSA isolates were biofilm producers. Resistance to two antibiotics such as erythromycin (72% vs 28%, P=0.01) and clindamycin (71% vs 29%, P=0.04) was higher among biofilm producers than non-biofilm producers. All strains had biofilm-forming genes and the prevalence of pvl gene was 41%. Most MRSA isolates belonged to SCCmec IVa (75%) and SCCmec III (18%). In PFGE technique, 5 common types and 2 single types were identified; Common type 1 with 37 isolates was dominant clone.Conclusion: We thus report preliminary data on the prevalence and distribution of MRSA genotypes in Tehran Children’s Hospital. These findings characterize the MRSA colonization dynamics in child patients in Iran and may aid the design of strategies to prevent MRSA infection and dissemination.Keywords: MRSA, biofilm formation, antibiotic resistance, SCCmec typing, PFGE

Background: Septicaemia is a leading cause of morbidity and mortality of infant's and childerens espicially in first week of their life, both in developed and underdeveloped countries.The aim of this research was to study of bacterial agents causing septicaemia and to determine their antibiotic suseptibility patternes. Materials and Methods : This was a descriptive study, it was performed during eight months from October 2011 till May 2011. In total 216 blood culture samples of children suspected of septicaemia in children health centre hospital were send to the laboratory for investigation. The bacterial identification was carried out by culturing and conventional biomedical tests. The antibiotic sensitivity tests were performed by disk diffusion method. These data are analyzed by SPSS and the results Expressed as relative frequencies. Results: Out of 216 tested samples 55(25.6%) were positive and 161 (74.54%) negative. The dominated bacteria was Escherichia coli (31.42%), followed by Staphylococcus aureus (22.86 %), Klebsiella pneumonia (20%)), Staphylococcus epidermidis (14.28%), Streptococcus pneumonia (2.86%), Salmonella typhi (2.86%), Enterobacter cloacae (2.86%) and Stenotrophomonas maltophilia (2.86%). In general gram-negative bacteria were isolated more than gram-positive. Staphylococcus bacteria were more resistant to antibiotics than other isolated bacteria, and were 100% resistant to penicillin. The enterobacteriaceae were more sensitive to norfloxacin, amikacin, tobramycin, and they were 100% resistant to ampicillin. Conclusion: The results obtained in this study showed that gram-negative bacteria are more responsible in septicaemia in children ward, and norfloxacin is the more effective antibiotic in comparison with others. [ABSTRACT FROM AUTHOR]