molecular characterization of class 1 integrons and gene cassettes in multidrug resistant (mdr) klebsiella spp. isolated from hospitalized and outpatients in iran, 2009.

background and objectives: klebsiella species are of the most common bacteria involved in nosocomial and urinary tract infections. genetic elements such as class 1 integrons have an important role in the resistance development. in this study, the share of class 1 integrons, the genetic characterization of the integron cassettes and pfge profiles of the clinical klebsiella isolates are evaluated in besat university hospital of sanandaj, iran. methods: isolates from 17890 clinical specimens were identified by api20e. antibiotic susceptibility testing and mic were done for mdr isolates. for investigating class 1 integrons and gene cassettes, pcr by inti1 integrase and 5΄-cs/3΄-cs were performed. integrated gene cassettes were analyzed by pcr-rflp and sequencing. pulsed-field gel electrophoresis was carried out for studying of clonality outbreak of isolates. results: thirty five klebsiella spp . were isolated and included 29 k. pneumoniae and six k. oxytoca . all the isolates were susceptible to carbapenems while other antibiotics showed high resistant profile. in all klebsiella spp . pcr for inti1 integrase and 5΄-cs/3΄-cs were positive (100%). sequencing for prevalent bands of internal variable regions between 5΄-cs/3΄-cs showed arr-5 , orfd-aaca4 and aad5- dfra17 . pfge analysis showed 18 clusters in k. pneumoniae with clonality relatedness in some cases but no relatedness among k. oxytoca isolates. conclusion: high prevalence of class 1 integron carrying gene cassettes confirms that integron-mediated antimicrobial gene cassettes are important in klebsiella spp. resistance profile. clone diffusions of mdr klebsiella spp. which harbor class 1 integrons have threaten the potential in the resistance development in our clinical settings.