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Soheila Habibi Ghahfarokhi, 1 Mehrdad Mosadegh, 1 Ali Ahmadi, 2 Mohammad Reza Pourmand, 1 Mohammad Azarsa, 3 Mohammad Rahbar, 4 Bahram Nikmanesh 5 1Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran; 2Molecular Biology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran; 3Department of Microbiology, Khoy University of Medical Sciences, Khoy, Iran; 4Department of Microbiology, Reference Health Laboratories Research Center, Ministry of Health and Medical Education, Tehran, Iran; 5Department of Medical Laboratory Sciences, School of Allied Medical Sciences, Tehran University of Medical Sciences, Tehran, IranCorrespondence: Mohammad Reza PourmandDepartment of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Poursina St., Keshavarz Blvd., Tehran 1417613151, IranTel/Fax +98 21-88-95-4910Email mpourmand@tums.ac.irIntroduction: Encapsulated Streptococcus pneumoniae strains cause high morbidity and mortality, mainly in countries with no pneumococcal conjugate vaccines (PCVs) immunization program. This study investigated the epidemiological changes of S. pneumoniae isolates including serotype distribution and antimicrobial susceptibility in Tehran, Iran.Methods: A total of 80 S. pneumoniae samples were collected from patients admitted to Shariati hospital over two periods. Half of the isolates were collected from February to September 2017 and the other half from July 2018 to March 2019. The antimicrobial susceptibility testing and PCV-13 serotype coverage of S. pneumoniae isolates were evaluated among patients with invasive and non-invasive infections.Results: The most common serotypes were 23F (17.5%), 14 (16.3%), 3 (16.3%) 19F (12.5%), and 19A (12.5%) in the present study. The vaccine coverage rates of PCV-7, PCV-10 and PCV-13 were 52.6%, 52.6%, and 83.7%, respectively. S. pneumoniae isolates with the serotype of the PCV-13 showed an increasing trend during the study. Nearly half of the S. pneumoniae strains were MDR, while MDR serotype 19A increased (40%) during the study periods. A small minority of isolates (16%) belonged to non-vaccine serotypes, 65% of which were assigned to MDR. In general, the frequency of penicillin resistant and MDR strains were estimated about 27.5% and 51%, respectively. An increase was observed in resistance to erythromycin and co-trimoxazole.Conclusion: The results showed that majority of the circulating serotypes in our study are related to PCV-13 serotypes. The use of conjugate vaccine in the immunization program and surveillance of antimicrobial resistance can be effective in reducing the pneumococcal clinical burden.Keywords: Streptococcus pneumoniae, serotype, pneumococcal conjugate vaccine, PCV, antibiotic susceptibility, multi-drug resistance, MDR

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