محمد مهدی سلطان دلال - ۱,۲Food Microbiology Research Center, Tehran University of Medical Sciences, Tehran, Iran ,Division of Microbiology, Dept. of Pathobiology, School of Public Health, Tehran University of Medical Sciences. Tehran, Iran..
عبدالعزیز رستگار لاری - Antimicrobial Resistant Research Center, Tehran University of Medical Sciences, Tehran, Iran.
روناک بختیاری - Division of Microbiology, Dept. of Pathobiology, School of Public Health, Tehran University of Medical Sciences. Tehran, Iran.
بهرام نیک منش - Laboratory, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran
محمدکاظم شریفی یزدی - ۵,۶Zoonosis Research Center, Tehran University of Medical Sciences, Tehran, Iran ,Dept. of Medical Laboratory Sciences, School of Para Medicine, Tehran University of Medical Sciences. Tehran, Iran..

Background and Objective: Attention has largely been focused on appearance of multiple drug resistance enterococci in the last ۲۰ years. One of the methods to overcome this problem is to combine different antibiotics in order to increase antimicrobial activity and reduce toxicity. The combination of fluor quinolones with other antibiotics has been widely investigated. The aim of this study was to investigate the synergistic effect of ciprofloxacin in several antibiotics Beta-lactam (piperacillin, ceftazidime and imipenem) on isolated enterococci. Materials and Methods: In this cross sectional study, ۶۷ Streptococci strains were isolated from clinical samples from March to September ۲۰۱۲. The serial broth dilution method in test tubes was used for the MIC, and the check board Format was used for the synergistic effect of ciprofloxacin with Beta-lactam antibiotics. The synergistic effect was determined with four- fold reduction of initial MIC. Results: Totally, ۶۷ strains of Streptococci were used, in which ۵۰ strains (۷۴.۶%) were enterococci, ۶(۹%) were group B streptococcus, ۵(۷.۵%) were non-group A streptococci, ۲ (۳%) were pneumococci, and ۲ were strains of alpha streptococci (۳%), respectively. All results were determined by the MIC and MBC of each antibiotic individually and also in combination with ciprofloxacin. Conclusion: The effect of ciprofloxacin on other antibiotics was indifferent, and the synergistic effect was not observed.

Keywords: Enterococcus, Streptococcus, Synergism, Ciprofloxacin, Beta- lactam, MIC, MBC