fa تحقيقي Original Paper <div> <p><strong>Abstract</strong></p> <p><strong>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Background and Objective</strong>: Due to the continuous increase of multidrug-resistant <em>Acinetobacter baumannii</em> strains around the world, decision making for an effective treatment of infections caused by this organism depends on the results of antimicrobial susceptibility tests. In this study, the validity of disk diffusion and E-test methods was assessed by their comparison with the reference method of microbroth dilution for three antibiotics of tetracycline, doxycycline and minocycline.</p> <p><strong>&nbsp;&nbsp;&nbsp;&nbsp; Methods</strong>: Total of 68 <em>A. baumannii</em> isolates were obtained from patients hospitalized in the burn center of Shahid Motahari Hospital in Tehran, Iran. Susceptibility of the <em>Acinetobacter </em>isolates was evaluated using the disk diffusion, E-test and microbroth dilution methods, according to the guidelines of Clinical and Laboratory Standards Institute.</p> <p><strong>&nbsp;&nbsp;&nbsp;&nbsp; Results</strong>: Among the isolates, 82.3% were tetracycline-resistant (with minimum inhibitory concentration 50 (MIC₅₀) and MIC₉₀ of 32 and more than 32 &micro;g/ml, respectively and 41.2% were doxycycline-resistant (with MIC₅₀ and MIC₉₀ of 4 and more than 32 &micro;g/ml, respectively). Minocycline, with resistance of up to 13.3% (MIC₅₀ and MIC₉₀ of 1 and 8 &micro;g/ml, respectively) showed the highest antimicrobial activity against the <em>A. baumannii</em> isolates. Antimicrobial susceptibility of bacteria was different depending on the type of methods used. No very major error was observed in any of the methods of susceptibility testing. Overall, the level of major and minor errors in the E-test was lower than the disk diffusion method.</p> <p><strong>&nbsp;&nbsp;&nbsp;&nbsp; Conclusion</strong>: The results of this study indicate that minocycline has notably high antimicrobial activity against <em>A. baumannii</em> compared to other antibiotics of the tetracycline group.</p> <p></p> </div> Acinetobacter baumannii, Tetracyclines, Minimum inhibitory concentration. 44 49 http://mlj.goums.ac.ir/browse.php?a_code=A-10-1-383&slc_lang=fa&sid=1 Abdollah Ardebili 100319475328460010871 100319475328460010871 Yes Faculty of Medicine, Laboratory Sciences Research Center, Golestan University of Medical Sciences, Gorgan, Iran Malihe Talebi 100319475328460010872 100319475328460010872 No Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran Abdolaziz Rastegar Lari 100319475328460010873 100319475328460010873 No Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran