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Setareh Mamishi,1,2 Zohreh Shalchi,3 Shima Mahmoudi,1 Reihaneh Hosseinpour Sadeghi,1 Mohammad Taghi Haghi Ashtiani,4 Babak Pourakbari1 1Pediatric Infectious Diseases Research Center, Tehran University of Medical Sciences, Tehran, Iran; 2Department of Infectious Diseases, Pediatrics Center of Excellence, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran; 3Department of Pediatrics, Hamadan University of Medical Sciences, Hamadan, Iran; 4Department of Pathology, School of Medicine, Tehran University of Medical, Sciences, Tehran, IranCorrespondence: Babak PourakbariPediatric Infectious Diseases Research Center, Children Medical Center Hospital, School of Medicine, Tehran University of Medical Sciences, No. 62, Gharib St., Keshavarz Blvd, Tehran, IranTel/ Fax +98 021 6642 8996Email pourakbari@tums.ac.irIntroduction: Urinary tract infection (UTI) is one of the most common bacterial infections in childhood, and the increasing rate of antibiotic resistance to the commonly prescribed antimicrobial agents against it has become a major concern. The aim of this study was to determine the antibiotic resistance and genotyping of bacteria isolated from urine cultures in patients referred to the Children’s Medical Center, Tehran, Iran.Methods: During the 1-year period, antimicrobial susceptibility profiles of strains isolated from patients with UTI were determined. Typing of the isolates causing nosocomial infections was performed by random amplified polymorphic DNA (RAPD) analysis, and the results were analyzed by Gelcompar II software.Results: In this study, 203 children (130 girls and 73 boys) were included. The patients’ age ranged from 1 day to 16 years (IQR average=4 months to 4 years). The most frequent isolated organisms were Escherichia coli (118 isolates, 58%), followed by Klebsiella pneumoniae (30 isolates, 15%). Sixty-two strains (18 strains of E. coli, 13 strains of K. pneumoniae, 11 strains of Enterococcus faecium, and five strains of Burkholderia cepacia complex) had criteria of nosocomial infection. A high resistance rate to trimethoprim-sulfamethoxazole (69%) and cefotaxime (60%) was reported in E. coli and K. pneumoniae strains, respectively. Pseudomonas aeruginosa strains showed high sensitivity to amikacin (100%). All E. faecium strains were susceptible to trimethoprim-sulfamethoxazole (100%), and 23% of the strains were resistant to vancomycin. The analysis of RAPD-typing revealed the presence of three clusters in E. coli, two clusters in E. faecium, and one clone in K. pneumoniae. Besides, four out of five isolates of B. cepacia complex had more than 90% genetic similarity.Conclusion: The most frequent isolated pathogen was E. coli, and an increasing rate of antibiotic resistance to the commonly prescribed antimicrobial agents such as trimethoprim/sulfamethoxazole and cephalosporins was observed. Moreover, the results of this study showed the presence of clones with ≥ 80% similarity in E. coli, K. pneumoniae, E. faecium, and B. cepacia complex isolates; therefore, the transmission of nosocomial infections from one patient to another or one ward to another is probable.Keywords: urinary tract infection, antibiotic resistance pattern, genotyping

Setareh Mamishi,1,2 Shima Mahmoudi,2 Naimeh Naserzadeh,1 Reihaneh Hosseinpour Sadeghi,2 Mohammad Taghi Haghi Ashtiani,3 Abbas Bahador,4 Mohammad Reza Abdosalehi,1 Maryam Rahmani,5 Babak Pourakbari2 1Department of Infectious Diseases, Pediatrics Center of Excellence, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran; 2Pediatric Infectious Disease Research Center, Tehran University of Medical Science, Tehran, Iran; 3Department of Pathology, Pediatrics Center of Excellence, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran; 4Department of Microbiology, Tehran University of Medical Sciences, Tehran, Iran; 5Pediatrics Center of Excellence, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, IranCorrespondence: Babak PourakbariPediatric Infectious Disease Research Center, Children Medical Center Hospital, Tehran University of Medical Sciences, 62 Gharib Street, Keshavarz Blvd, Tehran, IranTel +98 21 6642 8996Fax +98 21 6642 8996Email pourakbari@tums.ac.irBackground and aim: Hospital-acquired infection (HAI) is a major problem worldwide. Understanding patterns of bacterial etiology and antibiotic susceptibility is vital to combating HAI. Besides, typing of isolates is important to establish the intra-hospital surveillance of resistant clones. In this study, we aimed to evaluate antibiotic resistance and genotyping of a number of gram-negative bacteria (GNB) causing HAI in patients who were referred to Children’s Medical Center.Methods: During the 6-month period, antimicrobial susceptibility profiles of GNB isolates recovered from patients in Children’s Medical Center were determined. Typing of common GNB was performed by random amplified polymorphic DNA (RAPD) analysis and the results were analyzed by Gelcompar II software.Results: In total, 142 (1.1%) gram-negative bacterial strains were isolated, among which 59.2% were from males. The most organisms were isolated from blood (63%) followed by wounds (13.7%). The greatest proportion of strains came from intensive care units (51%). Low sensitivity of Acinetobacter baumannii to common antibiotics and high resistance of Enterobacter spp. To cefotaxime (100%) were reported. The most efficient antibiotics for Escherichia coli strains were amikacin (84%) and gentamycin (81%). However, just 12.5% of Serratia marcescens strains were resistant to trimethoprim-sulfamethoxazole. The analysis of RAPD-typing revealed the presence of one clone in A. baumannii and E. coli and two clones in Klebsiella pneumoniae, whereas the trend varied completely in Pseudomonas aeruginosa strains and Enterobacter spp.Conclusion: The results of this study showed a possibility of an outbreak in the Children’s Medical Center. Since there is a possibility of transmission of an infection from one patient to another, high attention should be paid to the basic methods of preventing infection.Keywords: hospital-acquired infection, gram-negative bacteria, antibiotic resistance