title: Expression of MexAB-OprM efflux pump system and susceptibility to antibiotics of different Pseudomonas aeruginosa clones isolated from patients hospitalized in two intensive care units at University Hospital in Bialystok (northeastern Poland) between January 2002 and December 2009.
abstract: We investigated the genetic similarities and expression of the MexAB-OprM efflux pump system in different clones of multiresistant Pseudomonas aeruginosa strains collected from 2002 to 2009 at two intensive care units (ICU). Regulatory and structural genes mexB, mexR, and mexA were found in 99%, 98%, and 94% of tested strains, respectively. The presence of class 1 integron was found in 90% of the strains, while class 2 integron in only one strain (Psa506). Class 3 integron was not found in any of the tested strains. Among the eleven clones identified, only two clones, I and D, exhibited higher levels of mexB gene expression than the other clones. Clone I had the highest expression (FC = 10.36, p < 0.05). The results of our study indicated a high level of MexAB-OprM pump expression in groups of strains isolated in the years 2008-2009 (FC = 12.92, p < 0.03) and 2002-2006 (FC = 5.14, p < 0.03). There were no statistically significant differences in resistance to all tested antibiotics among the various clones. The high level of antimicrobial resistance may have been due to the coexistence of different resistance mechanisms among the studied P. aeruginosa strains. However, this does not exclude the contribution of the MexAB-OprM pump, particularly in resistance to meropenem and ciprofloxacin.
authors.affiliation: Department of Microbiological Diagnostics and Infectious Immunology, Faculty of Pharmacy, Medical University, Bialystok.
authors.forename: Paweł
authors.initials: P
authors.lastname: Sacha
authors.forename: Piotr
authors.initials: P
authors.lastname: Wieczorek
authors.forename: Dominika
authors.initials: D
authors.lastname: Ojdana
authors.forename: Tomasz
authors.initials: T
authors.lastname: Hauschild
authors.forename: Robert
authors.initials: R
authors.lastname: Milewski
authors.forename: Sławomir
authors.initials: S
authors.lastname: Czaban
authors.forename: Bogusław
authors.initials: B
authors.lastname: Poniatowski
authors.forename: Elżbieta
authors.initials: E
authors.lastname: Tryniszewska
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D006785:Hospitals, University; D006801:Humans; D007362:Intensive Care Units; D026901:Membrane Transport Proteins / Q000235:genetics*; D011044:Poland; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D026901:Membrane Transport Proteins; C118598:MexA protein, Pseudomonas aeruginosa; C118597:MexB protein, Pseudomonas aeruginosa; C402263:OprM protein, Pseudomonas aeruginosa
keywords: MexAB-OprM expression; Pseudomonas aeruginosa; clones; susceptibility to antibiotics