Detection of VEB-1, OXA-10 and PER-1 genotypes in extended-spectrum b-lactamase-producing Pseudomonas aeruginosa strains isolated from burn patients Akbar Mirsalehian a, *, Mehdi Feizabadi a , Farrokh A. Nakhjavani a , Fereshteh Jabalameli a , Hamidreza Goli a , Narges Kalantari b a Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran b School of Medicine, Babol University of Medical Sciences, Babol, Iran Pseudomonas aeruginosa is one of the most important causes of nosocomial infections and has in recent years been considered to be multi-drug or pan-drug resistant to many antibiotics, including b-lactams [1,2]. Overproduction of chromosomal AmpC cephalosporinase is associated with the resistance to extended-spectrum b-lactamases (ESBLs) in P. aeruginosa. In addition, a non-enzymatic mechanism, such as drug efflux or outer-membrane impermeability, is associated with resis- tance [3]. Various classes of ESBLs (A, B and D) have been found recently in P. aeruginosa. Five types of class A ESBLs (PER, VEB, GES and IBC, TEM and SHV) were recently reported in P. aeruginosa; however, these were found in limited regions [4]. The PSE, OXA and PER types are the most common ESBLs found in P. aeruginosa isolates [5–7]. OXA-10 (PSE-2), an enzyme within the class D ESBLs, is responsible for a high level of resistance to carboxypenicillins, ureidopenicillins (piperacil- lin) and cephalosporins in P. aeruginosa isolates [8]. The PER-1 and VEB-1 types belong to class A enzymes and relate to a high burns xxx (2009) xxx–xxx article info Article history: Accepted 26 January 2009 Keywords: ESBL Pseudomonas aeruginosa Burn patients abstract Resistance of Pseudomonas aeruginosa strains to the broad-spectrum cephalosporins may be mediated by the extended-spectrum b-lactamases (ESBLs). These enzymes are encoded by different genes located on either chromosomes or plasmids. This study aimed to investigate the prevalence of ESBLs and antimicrobial susceptibilities of P. aeruginosa isolated from burn patients in Tehran, Iran. Antimicrobial susceptibility of 170 isolates to cefpodoxime, aztreo- nam, ciprofloxacin, ofloxacin, ceftazidime, cefepime, imipenem, meropenem, cefotaxime, levofloxacin, piperacillin–tazobactam and ceftriaxone was determined by disc agar diffusion test. Polymerase chain reaction (PCR) amplification of the genes encoding OXA-10, PER-1 and VEB-1 was also performed. All isolates (100%) were resistant to ceftazidime, cefotaxime, cefepime and aztreonam. Imipenem and meropenem were the most effective anti-pseudo- monal agents. The results revealed that 148 (87.05%) of the isolates were multidrug resistant and 67 (39.41%) of the isolates were ESBL positive. Fifty (74.62%), 33 (49.25%) and 21 (31.34%) strains among 67 ESBL-producing strains amplified bla OXA-10 , bla PER-1 and bla VEB-1 respectively. In conclusion, the high prevalence of multidrug resistance (87.05%) and production of OXA-10, PER-1 and VEB-1 genes in P. aeruginosa isolates in burn patients confirm that protocols considering these issues should be considered in burn hospitals. # 2009 Elsevier Ltd and ISBI. All rights reserved. * Corresponding author: Tel.: +98 21 8955810; fax: +98 21 8955810. E-mail address: mirsaleh@sina.tums.ac.ir (A. Mirsalehian). JBUR-2998; No of Pages 5 Please cite this article in press as: Mirsalehian A, et al. Detection of VEB-1, OXA-10 and PER-1 genotypes in extended-spectrum b- lactamase-producing Pseudomonas aeruginosa strains isolated from burn patients. Burns (2009), doi:10.1016/j.burns.2009.01.015 available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/burns 0305-4179/$36.00 # 2009 Elsevier Ltd and ISBI. All rights reserved. doi:10.1016/j.burns.2009.01.015