Downloaded from www.microbiologyresearch.org by IP: 54.70.40.11 On: Thu, 06 Dec 2018 22:28:52 Limited genetic diversity and extensive antimicrobial resistance in clinical isolates of Acinetobacter baumannii in north-east Iran Hadi Farsiani, 1,2,3 3 Arman Mosavat, 1,2,3 3 Saman Soleimanpour, 1,2,3 Mahbobeh Naderi Nasab, 2,3 Himen Salimizand, 1,2,3 Saeid Amel Jamehdar, 2,3 Kiarash Ghazvini, 2,3 Ehsan Aryan 2,3 and Ali-Asghar Baghani 1,2,3 Correspondence Saman Soleimanpour soleimanpour.saman@yahoo.com or soleimanpours881@mums.ac.ir 1 Student Research Committee, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran 2 Antimicrobial Resistance Research Center, Mashhad University of Medical Sciences, Mashhad, Iran 3 Department of Microbiology and Virology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran This study determined the mechanisms and patterns of antimicrobial resistance among the isolates obtained from different wards of a teaching hospital in the city of Mashhad in north-east Iran. Between January 2012 and the end of June 2012, 36 isolates of Acinetobacter baumannii were collected from different wards of Ghaem Hospital. Antimicrobial susceptibility testing and epsilometer testing (E-test) were performed. The genetic resistance determinants of A, B and D classes of b-lactamases, aminoglycoside modifying enzymes (AMEs), efflux pumps and ISAba1 elements were assessed by PCR. Repetitive extragenic palindromic element (REP)-PCR was performed to find the genetic relatedness of the isolates. Colistin was the most effective antibiotic of those tested, where all isolates were susceptible. E-test results revealed high rates of resistance to imipenem, ceftazidime and ciprofloxacin. The majority of isolates (97 %) were multidrug-resistant. OXA-51, OXA-23 and tetB genes were detected in all isolates, but OXA- 58, IMP and tetA were not detected. The prevalence of OXA-24, bla TEM , bla ADC , bla VIM and adeB were 64, 95, 61, 64 and 86 %, respectively. ISAba1 was found to be inserted into the 59 end of OXA-23 in 35 isolates (97 %). Of the AMEs, aadA1 (89 %) was the most prevalent, followed by aphA1 (75 %). The band patterns reproduced by REP-PCR showed that 34 out of 36 isolates belonged to one clone and two singletons were identified. The results confirmed that refractory A. baumannii isolates were widely distributed and warned the hospital infection control team to exert strict measures to control the infection. An urgent surveillance system should be implemented. Received 14 February 2015 Accepted 15 May 2015 INTRODUCTION Acinetobacter baumannii is an opportunistic micro- organism that is of concern in hospital-acquired infections (Dijkshoorn et al., 2007). This pathogen mainly infects patients in intensive care units (ICUs) and was first reported in the USA in 1992 (Go et al., 1994); many hospital outbreaks have subsequently been reported worldwide (Erdem et al., 2014). Its propensity to acquire resistance genes allows A. baumannii to survive under selective antibiotic pressure (Visca et al., 2011). Antibiotics considered for effective treatment of A. baumannii infections include carbapenems, cephalosporins, aminoglycosides, polymyxins (colistin) and tigecycline, solely and in combination; however, refrac- tory isolates have arisen with the exertion of resistance genes (Rahal, 2006). Resistance to carbapenems is mainly mediated by carbapenem-hydrolysing oxacillinases (OXA-23, OXA- 24/40, OXA-51 and OXA-58) and metallo-b-lactamases (MBLs; IMP, VIM, GIM, SIM and SPM) (Higgins et al., 3These authors contributed equally to this work. Abbreviations: AME, aminoglycoside modifying enzyme; CSF, cerebro- spinal fluid; ESBL, extended spectrum b-lactamase; ICU, intensive care unit; IM, internal medicine; IS, insertion sequence; MBL, metallo-b- lactamase; MDR, multidrug-resistant; PED, paediatrics; REP-PCR, PCR amplification of repetitive extragenic palindromic elements; SUR, surgery. Journal of Medical Microbiology (2015), 64, 767–773 DOI 10.1099/jmm.0.000090 000090 G 2015 The Authors Printed in Great Britain 767