Genetic Diversity of Pseudomonas aeruginosa Strains Isolated from Hospitalized Patients


1 Department of Clinical Anatomical Pathology,

2 Tracheal Disease Research Center, NRITLD

3 Department of Clinical Anatomical Pathology, Imam Hossein Hospital, Shahid Beheshti University M.C., TEHRAN-IRAN


Background: Pseudomonas aeruginosa is one of the most common nosocomial pathogens often causing major problems in Intensive Care Units. This study aimed to investigate the genotypic diversity of Pseudomomas aeruginosa strains isolated from hospitalized patients in National Research Institute of Tuberculosis and Lung Disease (NRITLD) with random amplified polymorphic DNA (RAPD) method and also to determine the antibiotic resistance pattern. Materials and Methods: Seventy three P. aeruginosa isolates from different specimens were analyzed. These strains were isolated from patient admitted in Intensive Care Unit (ICU) (31), non-ICU inpatient (40), and two environmental specimens one from ventilator and one from soap specimen in ICU. All strains were identified with biochemical testing and antimicrobial susceptibility testing which carried out according to National Committee for Clinical Laboratory Standards (NCCLS). Random Amplified Polymorphic DNA typing (RAPD) was used to study the genetic diversity of Pseudomonas aeruginosa using 2 sets of primers and electophoretic banding patterns were analyzed visually and by GelCompar ІІ software. Results: Phylogenic analysis of the RAPD pattern showed rates of genetic similarity ranging from 40-100%. Four epidemiologically and genetically related isolates (clones) each containing 2-3 isolates were identified. Most of them were from ICU. We detected high antimicrobial resistance rate to Chloramphenicol, Ceftriaxon, Cefepime, Ceftazidime (75-97%) and relatively low resistance rate to Imipenem, Amikacin, Ciprofloxacin and Gentamicin (42-53%). Conclusion: Although a few epidemiologically related clones are found with RAPD method, most of the isolates are probably emanate from the host itself. There is also a high rate of antibiotic resistance especially in ICU. (Tanaffos 2008; 7(1): 32-39)