Journal of Chromatography A, 979 (2002) 277–284 www.elsevier.com / locate / chroma Capillary electrophoresis study of outer membrane proteins of Pseudomonas strains upon antibiotic treatment a b, b b a * ´ ´ ´ ¨ ´ Tamas Kustos , Ildiko Kustos , Edit Gonda , Bela Kocsis , Gyorgy Szabo , c ´ Ferenc Kilar a ´ ´ ´ Department of Orthopaedics, Faculty of Medicine, University of Pecs, Szigeti ut 12, H-7643 Pecs, Hungary b ´ ´ ´ Department of Medical Microbiology and Immunology, Faculty of Medicine, University of Pecs, Szigeti ut 12, H-7643 Pecs, Hungary c ´ ´ ´ Central Research Laboratory, Faculty of Medicine, University of Pecs, Szigeti ut 12, H-7643 Pecs, Hungary Abstract Nosocomial wound infections by Pseudomonas aeruginosa strains have increasing importance in orthopaedic surgery. Outer membrane protein composition and cell-surface hydrophobicity of the bacteria have strong influence on adhesion to living tissues or artificial medical devices. Outer membrane proteins of five Pseudomonas strains ( KT 2, KT 7, KT 25, KT 28, KT 39 ) isolated from orthopaedic patients’ wounds and one standard strain NIH Hungary 170000 isolated from pus were examined. The capillary electrophoretic patterns of the outer membrane proteins were characteristic to each bacterial strains possessing different relative ratios of major and minor proteins. Antibiotic treatment of bacteria with three antibiotics, cefotaximum, amoxicillinum/clavulinic acid and amikacinum (applied often in prophylaxis and treatment of patients) induced changes in the electrophoretic profiles showing that outer membrane protein composition was altered significantly. The most pronounced alterations in the electrophoretic patterns after antibiotic treatment were obtained in the cases of the strains KT 2, KT 7 and KT 28. The amikacinum administration strongly decreased the relative percentage of the 38800 rel. mol. mass protein in KT 2 (from 20 to 6%), while the relative amount of the same protein increased significantly in KT 7 and KT 28 after cefotaximum treatment (from 2 to 16% and from 12 to 28%, respectively). Decrease in cell-surface hydrophobicity was also observed by salt aggregation test. The results obtained can be used to determine the therapeutic concentrations of antibiotics to induce changes in the adhesion properties of bacteria.  2002 Elsevier Science B.V. All rights reserved. Keywords: Pseudomonas aeruginosa; Antibiotics; Proteins 1. Introduction tract of patients receiving chemotherapy, or from the lower respiratory tract of ventilated patients [1]. The Pseudomonas aeruginosa, a gram-negative bac- P . aeruginosa strains are frequently responsible for terium, can be part of the normal microbial flora of nosocomial infections, such as nosocomial pneumo- the skin, throat and stool. It might be isolated more nias, septicaemias or surgical wound infections due frequently from hospitalized patients, especially from to, e.g. implantation of artificial medical devices [2]. the skin of burnt patients, from the gastrointestinal The adhesion and permanent attachment of bac- terial cells to the surface of living tissues or artificial medical devices depend mainly on the cell-surface *Corresponding author. Tel.: 136-72-536-001-1905; fax: 136- hydrophobicity and on specific interactions between 72-536-253. E-mail address: ildiko.kustos@aok.pte.hu (I. Kustos). microbial adhesins and surface receptors [3]. An 0021-9673 / 02 / $ – see front matter  2002 Elsevier Science B.V. All rights reserved. PII: S0021-9673(02)01521-2