title: Problematic clinical isolates of Pseudomonas aeruginosa from the university hospitals in Sofia, Bulgaria: current status of antimicrobial resistance and prevailing resistance mechanisms.
abstract: A total of 203 clinical isolates of Pseudomonas aeruginosa was collected during 2001-2006 from five university hospitals in Sofia, Bulgaria, to assess the current levels of antimicrobial susceptibility and to evaluate resistance mechanisms to antipseudomonal antimicrobial agents. The antibiotic resistance rates against the following antimicrobials were: carbenicillin 93.1 %, azlocillin 91.6 %, piperacillin 86.2 %, piperacillin/tazobactam 56.8 %, ceftazidime 45.8 %, cefepime 48.9 %, cefpirome 58.2 %, aztreonam 49.8 %, imipenem 42.3 %, meropenem 45.5 %, amikacin 59.1 %, gentamicin 79.7 %, tobramycin 89.6 %, netilmicin 69.6 % and ciprofloxacin 80.3 %. A total of 101 of the studied P. aeruginosa isolates (49.8 %) were multidrug resistant. Structural genes encoding class A and class D beta-lactamases showed the following frequencies: bla(VEB-1) 33.1 %, bla(PSE-1) 22.5 %, bla(PER-1) 0 %, bla(OXA-groupI) 41.3 % and bla(OXA-groupII) 8.8 %. IMP- and VIM-type carbapenemases were not detected. In conclusion, the studied clinical strains of P. aeruginosa were problematic nosocomial pathogens. VEB-1 extended-spectrum beta-lactamases appear to have a significant presence among clinical P. aeruginosa isolates from Sofia. Carbapenem resistance was related to non-enzymic mechanisms such as a deficiency of OprD proteins and active efflux.
authors.affiliation: Department of Microbiology, Medical University of Sofia, 2 Zdrave Street, 1431 Sofia, Bulgaria.
authors.forename: Tanya
authors.initials: T
authors.lastname: Strateva
authors.affiliation: Department of Microbiology, Medical University of Sofia, 2 Zdrave Street, 1431 Sofia, Bulgaria.
authors.forename: Vessela
authors.initials: V
authors.lastname: Ouzounova-Raykova
authors.affiliation: Laboratory of Clinical Microbiology, Alexander University Hospital, Medical University of Sofia, 1 Georgi Sofiiski Blvd, 1431 Sofia, Bulgaria.
authors.forename: Boyka
authors.initials: B
authors.lastname: Markova
authors.affiliation: Laboratory of Molecular Pathology, University Hospital of Obstetrics and Gynecology, Medical University of Sofia, 2 Zdrave Street, 1431 Sofia, Bulgaria.
authors.forename: Albena
authors.initials: A
authors.lastname: Todorova
authors.affiliation: Laboratory of Clinical Microbiology, Alexander University Hospital, Medical University of Sofia, 1 Georgi Sofiiski Blvd, 1431 Sofia, Bulgaria.
authors.forename: Yulia
authors.initials: Y
authors.lastname: Marteva-Proevska
authors.affiliation: Department of Microbiology, Medical University of Sofia, 2 Zdrave Street, 1431 Sofia, Bulgaria.
authors.forename: Ivan
authors.initials: I
authors.lastname: Mitov
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002031:Bulgaria / Q000453:epidemiology; D015780:Carbapenems / Q000494:pharmacology; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology; D024881:Drug Resistance, Bacterial; D029968:Escherichia coli Proteins; D006785:Hospitals, University; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D011552:Pseudomonas Infections / Q000453:epidemiology / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification*; D017422:Sequence Analysis, DNA; D001618:beta-Lactamases / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D015780:Carbapenems; D029968:Escherichia coli Proteins; C064821:beta-lactamase PSE-1; C119424:beta-lactamase VEB-1, E coli; D001618:beta-Lactamases