fa میکروب شناسی بالینی Clinical Microbiology مقاله پژوهشی Original Research Article <p style="text-align: justify;"><strong>Background:</strong> Multidrug-resistant (MDR) enterococci cause many problems for physicians and infection control specialists in the recent years. Hence, by the identification of antibiotic resistance patterns of enterococci in different geographical regions an appropriate strategy can be developed to prevent bacterial antibiotic resistance and provide effective treatment. The current study aimed at identifying enterococci via molecular methods and evaluating multi-drug resistance patterns in Enterococcus species isolated from nosocomial samples of some hospitals in Tehran, Iran.</p> <p style="text-align: justify;"><strong>Patients and Methods: </strong>The current study was conducted on 300 nosocomial samples from different hospitals in Tehran, Iran. The identified <em>Enterococcus</em> species of <em>E. faecalis</em> and <em>E. faecium</em> were isolated via biochemical testing and confirmed using polymerase chain reaction (PCR). The antibiotic resistance pattern was determined using the disc diffusion method according to the Clinical and Laboratory Standards Institute (CLSI) guidelines.</p> <p style="text-align: justify;"><strong>Results: </strong>The highest antibiotic resistance was observed against quinupristin-dalfopristin, tetracycline, and erythromycin. Minimum inhibitory concentration (MIC) of vancomycin against the isolated antibiotic resistant <em>Enterococcus</em> spp. was &ge;256 &micro;g/mL. According to the results of the current study, 69.6% of <em>E. faecalis</em> and 80% of <em>E. faecium </em>isolations showed multi-drug resistance.</p> <p style="text-align: justify;"><strong>Conclusion:</strong> Increase of antibiotic resistant bacteria, especially MDR species, is a severe health threatening problem worldwide. The increase of MDR bacteria limited therapeutic solutions to the patients with enterococcal infection, increased treatment costs, and led to transmission of resistant genes among bacteria. It is highly important to find antibiotic resistant patterns to compile guidelines for infectious diseases.&nbsp;</p> Enterococcus faecalis, Enterococcus faecium, Multi-drug Resistance, Polymerase Chain Reaction 60 67 http://modernmedlab.com/browse.php?a_code=A-10-1-25&slc_lang=fa&sid=1 Somayyeh Saeidi somayyeh206z500@yahoo.com 10031947532846001583 10031947532846001583 No Department of Microbiology, Pharmaceutical Sciences Branch, Islamic Azad University, Tehran, Iran Reza Mirnejad 10031947532846001584 10031947532846001584 Yes Molecular Biology Research Centre, Baqiyatallah University of Medical Sciences, Tehran, Iran Sara Masoumi Zavariani 10031947532846001585 10031947532846001585 No Department of Microbiology, Islamic Azad University, Varamin-Pishva Branch, Iran Shiva Rostasmzadeh 10031947532846001586 10031947532846001586 No Department of Microbiology, Islamic Azad University, Varamin-Pishva Branch, Iran