title: Investigation of OprD Porin Protein Levels in Carbapenem-Resistant Pseudomonas aeruginosa Isolates.
abstract: BACKGROUND
  The Pseudomonas aeruginosa porin OprD is a substrate-specific porin that facilitates the diffusion of basic amino acids, small peptides, and carbapenems into the cell. OprD-mediated resistance occurs as a result of decreased transcriptional expression of oprD and/or loss of function mutations that disrupt protein activity.
  
  
  OBJECTIVE
  In this study, we examined the level of oprD expression in P. aeruginosa clinical isolates to determine the contribution of OprD porins in carbapenem resistance.
  
  
  METHODS
  Included strains were divided into two groups, comprised of multidrug-resistant (MDR) and isolated carbapenem-resistant (ICR) strains. The transcription product level of oprD was identified using real-time polymerase chain reaction (qPCR).
  
  
  RESULTS
  Of the 18 clinical isolates, a decrease in the oprD level was found to be significant in 13 isolates. Nine of eighteen isolates with a significant decrease were determined in the first group and comprised MDR isolates that showed a statistically significant difference compared with the ICR group (P = 0.001). In the ICR group, oprD levels were found to be significantly low in 4 isolates. Six different patterns were determined by comparing band profiles in AP-PCR.
  
  
  CONCLUSIONS
  Although the data support the idea that the basic mechanism of imipenem resistance could be via the loss of oprD, they do not fully explain the role of oprD and indicate that other mechanisms may play an important role. Additionally, the significant decrease in the oprD levels in MDR strains suggests that oprD also plays a role in the emergence of both carbapenem and non-carbapenem resistance.
authors: Department of Medical Microbiology, Training and Research Hospital, Sakarya University, Sakarya, Turkey.
authors: Huseyin
authors: H
authors: Agah Terzi
authors: Department of Medical Microbiology, School of Medicine, Bulent Ecevit University, Zonguldak, Turkey.
authors: Canan
authors: C
authors: Kulah
authors: Department of Medical Microbiology, Training and Research Hospital, Sakarya University, Sakarya, Turkey.
authors: Ali
authors: A
authors: Riza Atasoy
authors: Department of Medical Microbiology, Training and Research Hospital, Sakarya University, Sakarya, Turkey.
authors: Ihsan
authors: I
authors: Hakki Ciftci
keywords: AP-PCR; OprD Porin Protein; Pseudomonas aeruginosa; oprD Expression; qPCR