title: ISPpu22, a novel insertion sequence in the oprD porin gene of a carbapenem-resistant Pseudomonas aeruginosa isolate from a burn patient in Tehran, Iran.
abstract: OBJECTIVE
  The oprD mutation and AmpC overproduction are the main mechanisms of intrinsic resistance to carbapenems such as imipenem and meropenem in Pseudomonas aeruginosa.
  
  
  METHODS
  In this study, we investigated intrinsic resistance to carbapenems including mutation of oprD and AmpC overproduction in a carbapenem-resistant P. aeruginosa isolated from a burn patient by phenotypic and molecular methods.
  
  
  RESULTS
  In our study, the carbapenem-resistant P. aeruginosa isolate was resistant to imipenem, meropenem, cefepime, gentamicin, ceftriaxone, carbenicillin, aztreonam and ciprofloxacin but was susceptible to ceftazidime and polymyxin B. The minimum inhibitory concentrations (MICs) against imipenem, meropenem and ceftazidime were 64 μg/ml, 16 μg/ml and 2μg/ml, respectively. The isolate was ESBLs and AmpC overproducer. No carbapenemase activity was detected by Modified Hodge test (MHT). This isolate was carrying only bla OXA-10 . PCR amplification and sequencing of oprD performed on isolate resulted in PCR product of 2647bp. Sequence analysis of the 2647bp product revealed insertion of a sequence of 1232 bp at position 8 in coding region of oprD.
  
  
  CONCLUSIONS
  According to the results of this study, oprD mutation and AmpC overproduction can cause the main mechanism of resistance of P. aeruginosa to carbapenems.
authors.affiliation: Department of Microbiology, School of Medicine, Kerman University of Medical Sciences, Kerman, Iran.
authors.forename: Davood
authors.initials: D
authors.lastname: Kalantar-Neyestanaki
authors.affiliation: Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Emaneini
authors.affiliation: Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Fereshteh
authors.initials: F
authors.lastname: Jabalameli
authors.affiliation: Department of Microbiology, School of Medicine, Lorestan University of Medical Sciences, Khoramabad, Iran.
authors.forename: Morovat
authors.initials: M
authors.lastname: Taherikalani
authors.affiliation: Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Akbar
authors.initials: A
authors.lastname: Mirsalehian
keywords: AmpC; Carbapenem-resistant P. aeruginosa; ISPpu22; oprD