en Epidemiologic Studies Epidemiologic Studies مقاله پژوهشی Original Research Article <p style="text-align: justify;"><span style="font-size:16px;"><span style="font-family:Times New Roman;"><strong new="" roman="" style="font-family: " times=""><span style="color:#ffffff;"><span style="background-color:#16a085;">Background and Objective:</span></span>&nbsp;</strong>As a significant cause of nosocomial infections, <i>Acinetobacter baumannii</i> has been linked to opportunistic infections. The assessment of clonal relatedness of <i>A. baumannii</i> isolates using typing methods like ERIC-PCR is beneficial for controlling conditions due to these resistant isolates. This research aims to study <i>Acinetobacter baumannii</i> resistant isolates to multidrug using typing methods like ERIC-PCR in clinics of Zanjan city.<br> <strong new="" roman="" style="font-family: " times=""><span style="color:#ffffff;"><span style="background-color:#16a085;">Materials and Methods:</span></span>&nbsp;</strong><span style="letter-spacing:-.1pt">In all, one hundred immunocompromised patients in ICU were included in the study and isolates of <i>A. baumannii</i> were extracted from their samples, and molecular typing using ERIC-PCR was performed on patients who were positive for aminoglycoside resistance-related genes (aph(2&#39;&#39;)-Id, ant(4&#39;&#39;)-Ia, ant(3&#39;&#39;)-I, aac(6&#39;&#39;)-Ib, aac(3)-I, aph(3&#39;&#39;)-I, aph(2&#39;&#39;)-Ib and aph (2&#39;&#39;)-Ic).</span><br> <strong new="" roman="" style="font-family: " times=""><span style="color:#ffffff;"><span style="background-color:#16a085;">Results:</span></span></strong>&nbsp;<span style="letter-spacing:-.1pt">67% of isolates had gentamicin resistance, and 63% had tobramycin resistance. The isolates tested positive for multidrug resistance (MDR) were all labeled as MDR strains. Furthermore, all antibiotics tested were ineffective against 32% of the isolates, while 91% could be deemed extensively drug-resistant (XDR). The aminoglycoside resistance gene aac(6&prime;)-Ib accounted for 79% of the cases, followed by ant(3&#39;&#39;)-I and aph(2&#39;&#39;)-Id (47%). Sixty-four percent of the isolates carried three or more aminoglycoside resistance genes simultaneously. A total of six types and 20 subtypes of patterns were obtained from ERIC-PCR.</span><br> <strong new="" roman="" style="font-family: " times=""><span style="color:#ffffff;"><span style="background-color:#16a085;">Conclusion:</span></span>&nbsp;</strong>In this study, aminoglycoside-resistant <i>A. baumannii</i> was found in a high percentage of ICU patients, mainly with the enzyme-modified aminoglycosides like aac(6&prime;)-Ib, aph(2&#39;&#39;)-Id and ant(3&#39;&#39;)-I. ERIC-PCR has also shown an increased level of diversity in <i>A. baumannii</i> isolates. Therefore, genetic diversity or clonal relatedness of <i>A. baumannii</i> isolates in clinical settings can be assessed using ERIC-PCR.</span></span></p> Acinetobacter baumannii, Molecular typing, Antibiotic resistance, ERIC PCR 544 552 http://journal.zums.ac.ir/browse.php?a_code=A-10-1599-6&slc_lang=en&sid=1 Leili Osanloo leiliosanloo139@yahoo.com 5200319475328460073694 5200319475328460073694 No Dept. of Microbiology, Zanjan Branch, Islamic Azad University, Zanjan, Iran Habib Zeighami Zeighami@zums.ac.ir 5200319475328460073695 5200319475328460073695 Yes Dept. of Microbiology, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran Fakhri Haghi haghi@zums.ac.ir 5200319475328460073696 5200319475328460073696 No Dept. of Microbiology, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran Reza Shapouri rezashapoury@yahoo.com 5200319475328460073697 5200319475328460073697 No Dept. of Microbiology, Zanjan Branch, Islamic Azad University, Zanjan, Iran Rasoul Shokri shokri32@yahoo.com 5200319475328460073698 5200319475328460073698 No Dept. of Microbiology, Zanjan Branch, Islamic Azad University, Zanjan, Iran